Retail

Shopify POS Duplicate Customers — How Point of Sale Creates Data Problems

Point of Sale transactions create duplicate customer profiles in Shopify. Learn why it happens and how to fix it.

6 min read•Last updated Feb 22, 2026

Why POS Creates Duplicate Customers

If you use Shopify POS for in-store sales, you've almost certainly accumulated duplicate customer profiles without realizing it. The POS system often creates a new customer profile linked to their credit card rather than their existing email-based online profile.

The POS Duplicate Problem

Credit card identification — POS terminals identify by payment method, not email

Staff may not ask for email — Busy cashiers skip the email field

Different email provided — Customer gives a different email at the register

No login required — In-store purchases don't ask for account login

Tap-to-pay anonymity — Apple Pay and Google Pay create minimal profile data

The Result

A customer who orders online as jane@gmail.com, buys in-store with Visa ending 4521, and makes another in-store purchase without email now has three separate customer profiles.

Impact on Retail & Omnichannel Stores

Problem	Impact
Fragmented purchase history	Can't see full customer journey across online + in-store
Wrong omnichannel LTV	Online-only LTV massively undervalues customers who also buy in-store
Broken loyalty programs	Points and rewards split across profiles
Inventory attribution	Can't accurately attribute demand signals
Email marketing gaps	In-store-only customers may have no email
Clienteling failure	Staff can't see customer's full history when they walk in

For omnichannel retailers, POS duplicates represent the single biggest data quality issue because online-to-offline behavior is inherently hard to track.

How to Fix POS Duplicates

Prevention: Capture Email at POS

Train staff: "Can I add your email for a digital receipt?"

Use POS receipt settings to prompt for email

Incentivize: "Enter your email for 10% off your next purchase"

Set up Shopify POS to display matching customer profiles during checkout

Detection: Find Existing POS Duplicates

MergeGuard detects POS duplicates by cross-referencing multiple signals:

Name + address matching

Same person, different email/no email

Phone number normalization

POS phone entries vs online phone entries

Order pattern analysis

Same products, same delivery locations

Credit card proximity

Multiple profiles with same last 4 digits at same address

Resolution: Merge POS Profiles

Install MergeGuard from the Shopify App Store

Run a scan — POS duplicates show up as Medium or High confidence

Review matches — verify the in-store profile matches the online customer

Merge — all in-store orders are consolidated with online orders

Monitor — MergeGuard alerts you when new POS duplicates appear

Case Study: Omnichannel Retailer

A Shopify Plus merchant with 15,000 customers and 3 retail locations discovered:

18%

duplicate rate attributed to POS transactions

+27%

average LTV increased after merging POS duplicates

+12%

email list grew as duplicate profiles were consolidated

24% → 38%

repeat purchase rate when in-store purchases were properly attributed

POS duplicates are invisible but expensive

The fix is automated detection and consistent email capture at the point of sale.

Fix POS Duplicates Free

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