Explainer
Why Shopify creates duplicate customers
Shopify ties each customer profile to the details a shopper gives, and a profile holds one email address. So when one person uses a second email, a phone number, a wallet email, a typo, or a name-only till sale, Shopify can create another profile. Its help pages describe merging as a manual action, so duplicates stay until someone merges them.
By MergeGuard team
Last updated
5 min read
On this page
Duplicate customers are normal on Shopify. Most come from shoppers doing ordinary things: checking out as a guest, using a different email, paying with a wallet. Knowing which cause is behind a duplicate helps you judge how strong the match is and whether you can stop it happening again.
Key insight
Shopify documents how profiles are made. None of its pages says how many duplicates exist, so count your own.
What Shopify documents
A few facts from Shopify’s own pages explain why duplicates form at all.
- Profiles come from shopper actions. Shopify’s Help Center says a profile “is created in your Shopify admin when a customer interacts with your business”: by signing up for your mailing list or an account, placing an order, or starting an order and abandoning the checkout.
- One email per profile. The same page says: “Each profile can have only one email address.” So a shopper who uses two emails can’t sit on one profile without a merge.
- A changed email doesn’t merge profiles. Shopify’s customer accounts page says “Changing an email address doesn’t merge profiles”, and a customer who signs in with an email that no profile uses gets a new profile automatically (Customer accounts).
- Staff create profiles at the till. Shopify’s POS page says staff can “create and manage customer profiles directly from the POS app”. The page doesn’t mention duplicates (POS customer management).
- Merging is something you start. Shopify’s Help Center describes merging as a manual action that merges two profiles at a time: “To merge more than 2 customers together, repeat the procedure for each additional profile.” The same page doesn’t describe Shopify finding duplicates for you.
Put together: Shopify creates profiles from whatever details it is given, and leaves combining them to you.
Shopify’s pages describe causes and tools, not prevalence. We also found no public study that measures how common duplicate customers are on Shopify stores, so this page gives no rate. To know yours, count your own duplicates.
The causes, and how we know about each
The table below marks each cause by its evidence. Shopify documents means Shopify’s own pages describe it. Merchant-reported means store owners describe it in the Shopify Community or on Reddit, which shows it happens to real stores but doesn’t prove how often.
| # | Cause | What happens | Evidence |
|---|---|---|---|
| 1 | Guest checkout with new details | A returning shopper types a different email or a phone number, and the order lands on a new profile | Merchant-reported (post 208) |
| 2 | A second or changed email | Work and home addresses, aliases, or a new address after a move | Merchant-reported (post 101) |
| 3 | Email typos | A mistyped address becomes its own customer, and the right one may be “already taken” when staff try to correct it | Merchant-reported (post 208) |
| 4 | Wallet and express checkout emails | Apple Pay or PayPal passes an email that differs from the store account | Merchant-reported (Apple Pay, post 22; PayPal, post 318) |
| 5 | In-store (POS) sales | A name-only record in store, then email or phone online, gives one person two or three histories | Merchant-reported (post 21) |
| 6 | Card-holder names at the till | Tapping a card can create a name-only customer before staff attach the right one | Merchant-reported (post 117) |
| 7 | Staff entry mistakes | Staff type the wrong customer details on an order | Merchant-reported (post 6) |
| 8 | Forgotten accounts | A shopper forgets their account or password and creates another | Merchant-reported (post 114) |
| 9 | Edited checkout links | A customer changes pre-filled details in a cart or draft-order link and a new record appears | Merchant-reported, one store (post 338) |
| 10 | Imports and connected apps | A CSV import or sign-up form from an email platform skips existing emails or creates new profiles | Merchant-reported, one operator (Reddit r/Klaviyo) |
| 11 | Deliberate extra accounts | A shopper makes a new account to use a one-time discount again | Merchant-reported (Shopify Community) |
Bots are a separate problem. One merchant reported large numbers of zero-spend customer records created by bots (Reddit r/ecommerce). Those are junk records rather than duplicates of real people, and they need a different cleanup.
What looks like a duplicate but isn’t
Some profiles share details because the people behind them share a life. Partners, flatmates, parents buying for children, and gift buyers sending to a friend all create profiles with the same address or phone (merchant report). They are different people, so they should stay as separate customers. In MergeGuard, you can mark relatives as family members. A Shopify merge is permanent: “After the profiles are merged, you can’t reverse the process.”
Which causes you can reduce
- Typos: fix them as soon as you spot them, so the shopper’s next order finds the right profile. See contact fixes.
- POS name-only records: ask staff to attach the customer by email or phone before taking payment.
- Phone-only checkouts: one merchant turned off checkout by phone to cut phone-only duplicates, at the cost of a less flexible checkout (merchant report).
- Imports: check how your import or connected app matches existing customers before you run it.
Second emails, wallets and forgotten accounts come from shoppers, and you can’t fully prevent them. For those, plan a regular review. The guest checkout guide walks through finding and merging them safely.
Sources
Related
- Guest checkout and duplicate customers in ShopifyWhy guest checkout splits one shopper across several Shopify profiles, how to find those duplicates safely, and what Shopify’s merge rules mean.
- Duplicate customer profileA duplicate customer profile is a second Shopify profile for the same person. Learn how to spot one, how to tell it from relatives, and what to do next.
- Identity resolutionIdentity resolution decides which customer records belong to the same person, using email, phone and address. See how it works in Shopify and email platforms.
- Find and review duplicatesMergeGuard scans your Shopify customers, groups duplicate profiles and shows which name, email, phone and address details match, so you decide what merges.
- Contact fixesMergeGuard flags mistyped and throwaway customer emails in Shopify and fixes typos after you confirm the count. Undo a fix once. Subscriptions stay as they are.
- Why you can’t merge customers in Shopify POS, and what to do insteadShopify’s reply says merging customer profiles is not in POS. See what that costs a busy shop, what to do instead and where MergeGuard helps.