Why Shopify stores end up with duplicate Klaviyo profiles, and what they cost

Klaviyo keeps one profile for each identity it recognizes, and it bills for the profiles it can email. A shopper who reaches your account under two identifiers can end up as two profiles, and both count. This guide follows how that happens for a Shopify store, what Klaviyo says it costs, and what Klaviyo’s help pages say to check before you clean up. We read those pages on October 26, 2026. Klaviyo changes its plans and its features, so check your own account.

How one shopper becomes two Klaviyo profiles

Klaviyo matches data to a profile through identifiers. Its help ranks them as the profile ID, an external ID, the email address, the phone number and, for a mobile app, an anonymous app ID. Two records stay apart until an action links their identifiers. The help pages give these routes to a second profile.

• A second email address. Klaviyo’s page on Multi Email Profiles says shoppers “might sign up with their personal Gmail, check out with a work address, and click a link from a third address”. When those addresses are not linked to one profile, their activity spreads across separate profiles. That page applies to accounts that have Multi-Email Profiles turned on.
• A phone number alone. A customer who texts a subscribe keyword gets a profile with only a phone number, apart from their email profile. Klaviyo merges the two when a later action sends both, such as a checkout with an email address and a phone number. A subscribe keyword on its own does not tell Klaviyo which email profile sent it, so the two can stay apart.
• A typo. Klaviyo’s page on merging profiles names a typo in an email address as a reason one contact has two profiles.
• An address that comes back. When Klaviyo merges two profiles, the source profile is deleted. If an event later arrives with that profile’s original email address and no existing profile holds it, Klaviyo creates a new profile for it.

Shopify adds its own routes. Klaviyo’s data reference says it creates a unique profile for every customer it syncs from Shopify, so a shopper with two Shopify profiles can arrive as two Klaviyo profiles. Our guide to why Shopify creates duplicate customers lists those routes. The sync can also run the other way: with all profiles chosen, Klaviyo creates Shopify customers for Klaviyo profiles that do not exist there yet, including profiles from imports. On our reading, an extra address in Klaviyo can then become an extra customer in Shopify.

What Klaviyo merges by itself

Klaviyo checks for chances to merge as customers act. Its help describes a merge when one action links two identifiers, for example a checkout that carries both an email address and a phone number. It also describes accounts with Multi-Email Profiles, where an update that matches an existing profile by its external ID, such as a customer ID from the store, and brings a new email address can keep the old address as a secondary one.

The pages we read describe merges that need a link between the identifiers. They do not describe Klaviyo joining two profiles that have different email addresses and nothing that connects them. Those stay apart until a person merges them by hand or a later action links them.

What duplicate profiles cost

Klaviyo’s page on Multi Email Profiles lists what separate profiles can lead to:

• duplicate profiles cluttering your account
• broken automation flows and missed triggers
• inconsistent consent and suppression records
• fragmented data that makes personalization harder
• inflated contact counts and skewed analytics

The billing cost follows from how Klaviyo counts. Its billing page says “Any profile, regardless of consent status, that can be emailed through Klaviyo is considered an active profile”, and your plan has to cover your active profile count. A person held as two emailable profiles takes up two places in that count. If the count passes your plan’s limit, Klaviyo moves you to a plan that covers it for the next billing cycle.

Profiles that are suppressed from email drop out of the count once Klaviyo has processed the suppression, and a phone number alone does not count toward the plan. After a large cleanup the count shown in billing can take up to 72 hours to refresh, and a lower plan starts in your next billing cycle. For a way to put a number on your own duplicates, see the estimate in how email platforms bill for contacts.

What to check before you merge Klaviyo profiles

Klaviyo’s pages set out the rules in plain terms.

1. A merge is permanent. Klaviyo says “Merging profiles is permanent and cannot be undone. Only merge profiles that belong to the same person.”
2. A merge adds no consent. It combines the subscription information that already exists and does not collect new consent. Klaviyo says to review the kept profile’s consent and suppression status before you send, and to check each channel separately.
3. A merge moves more than the email address. The kept profile receives the other profile’s events and list memberships. Active coupons stay with the old profile. Flows that both profiles were in can stop for one of them.
4. Deleting is a different step. Klaviyo says deleting a profile “permanently removes its data and cannot be undone”. Suppressed profiles stay in the account for historical reporting, as Klaviyo’s billing page says.

The same rules apply to the Shopify side of your cleanup. Shopify merges are permanent as well, and a merged Shopify profile is subscribed if either profile was. What happens to email and SMS consent when you merge sets the two systems side by side.

A cleanup order that fits

1. Count first. Compare your emailable profiles with the people behind them, as in the billing guide.
2. Clean the source. Fewer duplicate customers in Shopify means fewer duplicate profiles flowing into Klaviyo.
3. Merge only profiles you are sure belong to one person.
4. Review consent and suppression on each kept profile before the next send.
5. Check your active profile count a few days later, and change your plan only when the new count has settled.