If you sell on Amazon, at some point you may come across a confusing situation: the same product appears under two different ASINs.

Perhaps you have found two virtually identical product listings. Amazon may have detected a potential duplicate in your catalogue. Or, while trying to create a new product, you may discover that a product page already exists for that exact item.

Although this might seem like a simple organisational issue, duplicate ASINs on Amazon can make catalogue management more complicated, split information across different pages and cause confusion for both sellers and customers.

Amazon also states that a new ASIN should not be created when the exact same product already exists in its catalogue.

So, what should you do if you find two ASINs for the same product? Can they be merged? What happens to the reviews? And how can you tell whether they really are duplicates?

Let’s go through it step by step.

What is an ASIN on Amazon?

ASIN stands for Amazon Standard Identification Number.

It is a unique ten-character identifier made up of letters and numbers that Amazon assigns to products in its catalogue.

Its purpose is relatively straightforward: to identify a product within Amazon and allow different offers for that item to be grouped together on the same product detail page.

This last point is important.

An ASIN identifies a product, not necessarily a seller.

Imagine a specific pair of headphones from a particular brand, in a particular model and colour. Several sellers may sell exactly the same headphones on Amazon, each with their own price, stock and terms.

They do not need to create separate product pages.

Their offers can all be associated with the same ASIN.

Amazon explains that ASINs are used to identify products, organise its catalogue and group different offers for the same item.

ASIN, SKU, EAN and GTIN: what’s the difference?

Before looking at duplicate ASINs, it is worth distinguishing between four concepts that are often confused:

ASIN

An ASIN identifies a product within Amazon’s catalogue. It is assigned by Amazon.

SKU

A SKU (Stock Keeping Unit) is a reference used by the seller to organise their own products and offers internally.

This means you may have different SKUs associated with the same ASIN.

That does not necessarily mean you have a duplicate ASIN.

GTIN

A GTIN (Global Trade Item Number) is a global identifier used to identify trade items.

GS1 is the organisation responsible for the global standards system used for these identifiers.

EAN

An EAN is one of the identifiers commonly used in Europe within the GS1 system.

Amazon may use identifiers such as GTINs, EANs or UPCs to verify which product you are trying to add to its catalogue.

The key difference can be summarised as follows:

An ASIN identifies a product within Amazon; a GTIN/EAN identifies it in a standardised way beyond Amazon; and a SKU helps you manage your own offer as a seller.

What is a duplicate ASIN?

A duplicate ASIN occurs when two different ASINs actually represent exactly the same product.

Imagine a brand sells a 500 ml insulated bottle.

The product already exists on Amazon under a specific ASIN.

Later, another product page is mistakenly created for exactly the same bottle: same brand, same model, same capacity, same colour and same features.

Amazon now has:

ASIN A → 500 ml insulated bottle
ASIN B → The exact same 500 ml insulated bottle

Instead of having different offers grouped together on a single product page, there are now two separate pages for the same item. This is precisely what should be avoided. Amazon acknowledges that duplicate pages can exist within its vast catalogue and has procedures for reviewing and, where appropriate, merging duplicate product pages.

Why are duplicate ASINs a problem?

Having two pages for the same product can cause several issues.

Traffic can be split

One customer may land on one ASIN while another ends up on the second listing. Instead of concentrating activity around a single product page, traffic may be divided between different pages. Amazon notes that duplicate pages can split traffic and create confusion for customers.

Product information may differ

Imagine one ASIN has five images and the other has seven. One has an updated description while the other still contains outdated information. One displays the correct model, while the other contains an incorrect attribute.

Customers may therefore find different information about exactly the same product depending on which page they visit.

They make catalogue management more complicated

The more products and marketplaces a seller manages, the more important it becomes to maintain a consistent structure for:

• ASIN.
• SKU.
• EAN or GTIN.
• Variations.
• Models.
• Versions.

Duplicates add an unnecessary layer of complexity.

Amazon may take action

Amazon’s ASIN creation policy states that sellers should not create a new ASIN when a product already exists in the catalogue. Instead, they should add their offer to the existing product.

Amazon also warns that incorrectly creating duplicate ASINs may affect ASIN creation privileges and even selling privileges.

Why are duplicate ASINs created?

Duplicate ASINs can arise for several reasons. Here are some of the most common.

1. Creating a product without checking whether it already exists

This is probably the most common scenario. A seller attempts to add a product to the catalogue and creates a new listing without realising that the exact same item is already available on Amazon.

That is why, before creating a new product, it is worth searching not only by name but also using information such as:

• Brand.
• Model.
• EAN.
• UPC.
• GTIN.
• Manufacturer part number.

If the product already exists, you would normally add your offer to the corresponding page rather than creating a new one.

2. Using an incorrect EAN or UPC

Amazon’s policy identifies the incorrect use of identifiers such as UPC, EAN, ISBN or JAN as a potential cause of duplicate listings. If the product’s identity is not configured correctly from the outset, inconsistencies may eventually appear in the catalogue.

3. Using different codes for the same product

Amazon also highlights the issue of assigning different product codes to identical items.

The same product should not artificially become two different products simply because a different identifier is used.

4. Creating a new identity when entering another marketplace

This is particularly important for European sellers. Suppose you already sell a product on Amazon Spain and want to expand into Germany, France or Italy.

Selling it in another marketplace does not automatically make it a different product. In fact, Amazon specifically identifies assigning a new UPC or EAN to the same product in each marketplace as an incorrect practice.

5. Incorrectly using a GTIN exemption

GTIN exemptions allow certain products to be created without a standard identifier in specific circumstances. However, using an exemption when the product is already correctly identified or already exists in the catalogue can contribute to inconsistencies and duplicate listings.

How can you tell whether two ASINs are really duplicates?

Before requesting a merge, you need to answer one fundamental question: Are we sure both ASINs represent exactly the same product?

Two products may look almost identical while actually being different references. To check, compare:

• Brand.
• Manufacturer.
• EAN, UPC or GTIN.
• Model.
• Size.
• Colour.
• Dimensions.
• Number of units.
• Materials.
• Packaging.
• Included accessories.
• Technical specifications.
• Product version or generation.

For example, a 500 ml bottle and a 750 ml bottle may belong to the same product range, but they are not the same product.

The same applies to two seemingly identical devices if they belong to different generations or contain different components.

For a merge to make sense, both pages should genuinely represent the exact same item.

Duplicate ASINs and variations are not the same thing

This is a common source of confusion. Imagine you sell a T-shirt available in:

• Red, size M.
• Red, size L.
• Blue, size M.
• Blue, size L.

These products may be grouped within a variation family, but they are not duplicate ASINs. Each combination represents a specific variation.

Amazon uses parent-child structures to group certain product variations, while merging duplicate pages serves a different purpose: resolving cases where two pages represent exactly the same item.

Therefore:

Different products that should belong to the same family → variation issue.

Different pages representing exactly the same product → potential duplicate ASIN.

Distinguishing between the two before making changes to your catalogue can save you a lot of trouble.

How do you merge two duplicate ASINs on Amazon?

If you have confirmed that two pages represent exactly the same product, you can ask Amazon to review whether they can be merged. Amazon provides a tool for requesting the merging of duplicate product pages.

There are two concepts you should understand during this process.

Target ASIN

The Target ASIN is the ASIN you want to retain as the main product page.

Source ASIN

The Source ASIN is the duplicate page that you want to merge into the Target ASIN.

Amazon will review the request to determine whether both pages meet the necessary requirements. Therefore, requesting a merge does not mean it will automatically be approved.

Which ASIN should you keep?

It can be tempting to base this decision solely on the number of reviews each listing has. However, before selecting the Target ASIN, you should check which page correctly represents the identity of the product.

Pay particular attention to:

• Correct GTIN/EAN association.
• Brand.
• Manufacturer.
• Model.
• Product attributes.
• Catalogue information.
• Associated offers.
• Inventory.
• Related advertising campaigns.
• Product presence in other marketplaces.

The aim of a merge should not simply be to keep whichever ASIN is most advantageous to you, but to correctly consolidate pages that represent the same product.

What happens to reviews when two ASINs are merged?

This is often one of sellers’ biggest concerns.

According to information provided by official Amazon moderators on Seller Central, when a valid merge is completed successfully, the history and reviews of both ASINs may be combined.

Amazon has also indicated that reviews may take approximately seven days to appear after the merge. However, there is one very important point to keep in mind: an ASIN merge is not a tool for transferring reviews from one product to another.

The pages must genuinely represent the same product and meet Amazon’s requirements.

Attempting to merge different products simply to consolidate their reviews would go against the purpose of the tool and may lead to catalogue and compliance issues.

Can Amazon reject a merge?

Yes. Just because two pages look identical at first glance does not mean Amazon will consider them eligible for a merge.

There may be differences in attributes such as:

• Brand.
• Manufacturer.
• GTIN.
• Size.
• Colour.
• Quantity.
• Packaging.
• Accessories.
• Model.
• Version.
• Technical specifications.

If Amazon rejects a merge request, the first step should be to find out what difference it has detected between the two products. From there, there are two possible scenarios.

The products really are different

In that case, they should not be merged.

The products are identical, but the catalogue contains incorrect information

In this case, you will need to identify which attribute is incorrect and gather documentation that proves what the correct information should be.

Depending on the situation, it may be useful to have:

• Manufacturer documentation.
• Product photographs.
• Packaging photographs.
• EAN/GTIN.
• Information registered with GS1.
• Brand-related documentation.

If the automated process does not resolve the issue, you may need to open a case with Seller Support and provide this documentation.

What role does GS1 play when there is an issue with an ASIN?

When there is a discrepancy relating to a product’s identity, GS1 data can be particularly relevant.

GS1 manages international product identification standards and offers Verified by GS1, a service that allows information associated with certain GTINs to be verified.

GS1 explains that marketplaces such as Amazon use its data to help verify product identities, reduce catalogue errors and correctly associate offers. This is why, particularly if you own a brand, it is important to maintain a consistent relationship between:

Product → GTIN/EAN → brand information → Amazon ASIN.

The larger your catalogue becomes, the more important it is to keep this information organised.

Can I reuse an ASIN for a new version of my product?

Here, it is important to distinguish between updating a listing and turning an old listing into a new product.

You can correct or improve information relating to the product that the ASIN genuinely represents.

However, you should not reuse an old product listing to represent a new version that has materially changed.

A new product page may be required if the manufacturer launches a new generation with significant differences in:

• Size.
• Materials.
• Features.
• Configuration.
• Model.
• Name.
• Functionality.

The principle is simple: Updating information about the same product is one thing. Turning an existing ASIN into a different product is another.

What happens if you rebrand the product?

A brand change should not simply be treated as a minor modification to an existing listing either.

Amazon places restrictions on changing the brand identity associated with a product and, depending on the nature of the change, you may need to create a new ASIN.

This also explains why two physically very similar products are not necessarily duplicates.

Product identity is not determined solely by dimensions or technical specifications. Brand and manufacturer are also part of the attributes Amazon uses to structure its catalogue.

Can Amazon merge ASINs automatically?

Yes. Amazon can detect duplicate pages within its catalogue and consolidate them when it determines that they represent the same product.

This is why it is so important to correctly configure:

• Brand.
• Manufacturer.
• GTIN/EAN.
• Model.
• Attributes.
• Variations.

A well-structured catalogue makes it easier for Amazon to correctly identify what each page represents.

What if Amazon merges two ASINs that are actually different?

The opposite situation can also occur. Amazon may incorrectly associate or merge pages that correspond to different products.

In this case, your goal is no longer to prove that they are duplicates, but rather the opposite: to demonstrate that they are two different products.

To do so, gather clear evidence of their differences:

• Different GTINs.
• Different models.
• Photographs.
• Packaging.
• Features.
• Brand.
• Manufacturer.
• Dimensions.
• Official product documentation.

The more objective the differences between the two items are, the easier it will be to document the issue with Amazon.

Duplicate ASINs when selling on Amazon Europe

International expansion deserves particular attention. Suppose a brand sells a product on Amazon Spain and later decides to enter Amazon Germany, France and Italy.

You are entering new marketplaces, but the physical product may still be exactly the same.

Amazon specifically identifies assigning a new EAN or UPC to the same product simply because it is being sold in another marketplace as an incorrect practice. Therefore, before creating new references during international expansion, it is worth checking how the product is structured within Amazon’s European catalogue.

Poorly managed expansion can result in:

• Duplicate listings.
• Catalogue issues.
• Inconsistent information.
• Identifier-related issues.
• Different pages for the same product.

If you plan to sell in several countries, catalogue management should form part of your expansion strategy from the outset.

How to avoid duplicate ASINs

Resolving catalogue issues can take time. Preventing them is usually much easier.

Search before you create

Before adding a new product, check whether it already exists. Search by:

• EAN.
• UPC.
• GTIN.
• Brand.
• Model.
• Name.
• Manufacturer part number.

Use the correct identifiers

Never reuse codes belonging to other products. The GTIN should correctly represent the product you are trying to sell.

Keep your catalogue organised

If you own a brand, document which identifier corresponds to each:

• Product.
• Variation.
• Size.
• Model.
• Generation.

A spreadsheet may be enough for smaller catalogues. As you grow, this information should become part of your product management processes.

Don’t create new codes simply because you are entering another country

Entering Amazon Germany, France or Italy does not automatically mean your product needs another identifier. First check how the product is structured within Amazon’s European catalogue.

Verify your GTINs

There are services that allow you to verify information associated with product identifiers. Particularly for brands with large catalogues, keeping this data correctly configured can help prevent future issues.

Checklist: what to do if you find two ASINs for the same product

If you have identified a potential duplicate ASIN, follow these steps:

1. Check that they really are the same product.

Do not request a merge simply because the listings look similar.

2. Compare the attributes.

Check the brand, manufacturer, GTIN/EAN, model, size, quantity, packaging and features.

3. Check the GTIN.

Verify that the identifier corresponds to the correct product.

4. Rule out a variation issue.

Two related variations are not necessarily duplicates.

5. Identify the Target ASIN.

Determine which page correctly represents the product.

6. Request a merge from Amazon.

Use the procedure available for duplicate product pages.

7. If Amazon rejects the request, investigate why.

Check which attributes are causing the discrepancy.

8. Gather documentation.

Manufacturer documentation, photographs, packaging, GTIN and GS1 data may be useful.

9. Contact Seller Support if necessary.

Clearly explain why both ASINs represent exactly the same item.

10. Review the outcome.

After a merge, check the catalogue, offers, inventory, reviews and related campaigns.

Frequently asked questions about duplicate ASINs on Amazon

Can a product have two ASINs on Amazon?

It is possible for two different pages to exist for exactly the same product, but Amazon may consider them duplicate pages. If the product already exists in the catalogue, a second ASIN should not deliberately be created for the same item.

Can two ASINs be merged?

Yes. Amazon has a procedure for requesting the merge of duplicate product pages. The products must meet the relevant criteria, and Amazon will review the request.

What is the Target ASIN?

It is the ASIN that will remain as the main product page when a merge is completed.

What is the Source ASIN?

It is the duplicate ASIN that you request to merge into the Target ASIN.

What happens to reviews when ASINs are merged?

Amazon has indicated through official Seller Central moderators that, when a valid merge is completed, the history and reviews of both ASINs may be combined. Reviews may take several days to appear after the process.

Can I merge two similar products?

They should not be merged simply because they are similar. For a duplicate-page merge, both pages should genuinely represent the same product.

Are ASIN and EAN the same thing?

No. An ASIN identifies a product within Amazon’s catalogue. An EAN is part of the GS1 international product identification system.

Are ASIN and SKU the same thing?

No. An ASIN identifies a product within Amazon, while a SKU is a reference used by the seller to manage their own offer internally.

Do I need another ASIN to sell the same product in Germany or France?

You should not deliberately create a new identifier for exactly the same product simply because you are moving to another marketplace. Before creating new pages as part of a European expansion, check how the product is structured within Amazon’s catalogue.

What happens if my product changes?

It depends on the change. If you are simply correcting information about the same product, the relevant listing can be updated. If there is a new version with material changes to its features or identity, a new product page may be required.

Good ASIN management starts before you build your catalogue

An ASIN may look like nothing more than a combination of ten characters, but behind that code is the identity of a product within Amazon’s catalogue.

And when a business starts managing tens, hundreds or even thousands of products, keeping that identity properly structured is no longer a minor detail.

Problems often begin with small inconsistencies: an incorrect EAN, a listing created twice, a new version published over an old product, or international expansion carried out without first reviewing the catalogue.

The best way to avoid duplicate ASINs is to establish one simple rule:

Before creating a new product page, check whether the product already exists and make sure its identifiers are correct.

And if you discover two ASINs that represent exactly the same item, don’t delete listings or make improvised changes. First check the attributes, identify which ASIN correctly represents the product and use Amazon’s procedure to request a merge where appropriate.

Good catalogue management may not be the most visible part of selling on Amazon, but it can prevent a lot of problems as your business starts to scale.

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