Skip to main content
E-Commerce Data Quality

Duplicate SKUs: The Silent Killer of E-Commerce Operations

Duplicate SKUs cause inventory errors, fulfillment mistakes, and financial reporting problems. Here's how to find and eliminate them before they cause a crisis.

Key Takeaways
  • Duplicate SKUs cause inventory miscounts, wrong shipments, and blended financial reports
  • They accumulate through manual entry errors, migrations, and import mistakes
  • COUNTIF on your SKU column identifies all duplicates in a CSV export in minutes
  • Fix: identify the canonical product for each SKU, reassign new SKUs to duplicates, update all systems
  • Prevent recurrence: centralize SKU assignment, use a consistent formula, check before import

What Happens When SKUs Collide

Every product and product variant in your store should have a unique SKU. When two different products share a SKU, your systems get confused — and the confusion shows up in the worst possible places.

Inventory miscounts: Your inventory management system thinks you have 50 units. In reality, you have 30 of Product A and 20 of Product B, but they're counted as one.

Wrong items shipped: A pick-and-pack workflow triggered by SKU may pull Product A when the customer ordered Product B. Returns, refunds, and angry reviews follow.

Financial reporting errors: Revenue and COGS reports aggregated by SKU show blended numbers that are meaningless for either product individually.

Vendor confusion: If you share SKUs with suppliers for purchase orders, a duplicate SKU creates ambiguity about what you ordered and what was received.

Sohovi automatically finds every duplicate in your dataset — including near-matches — and shows you exactly which rows are affected.

How Duplicate SKUs Happen

Duplicate SKUs are almost never intentional. They accumulate through:

  • Manual data entry by different team members with no centralized SKU assignment process
  • Platform migrations where SKUs from two systems got merged without a uniqueness check
  • Import errors where a SKU field was left blank and defaulted to a placeholder
  • Variants of one product sharing a parent SKU without a size/color suffix

Finding Duplicate SKUs in Your Catalog

Export your full product catalog to CSV. Isolate the SKU column. Use a COUNTIF formula:

=COUNTIF($A:$A, A2)

Copy this formula down for every row. Any value greater than 1 is a duplicate. Sort by this helper column to bring all duplicates to the top.

Fixing Duplicate SKUs

For each duplicate group:

  1. Identify which product the SKU "belongs to" — typically the first one to use it or the higher-volume product
  2. Assign a new, unique SKU to the other product(s)
  3. Update all connected systems: your platform, your warehouse management system, your supplier POs, your accounting software

Document the old and new SKU for every product you rename. This is your audit trail for reconciliation.

Preventing Future Duplicates

Centralize SKU assignment: One person or one system assigns all new SKUs. No one generates their own.

Use a SKU formula: Many brands use a format like [Category]-[Brand]-[Size]-[Color]. Consistent structure reduces collisions.

Check before import: Before importing any new products, check the incoming SKU list against your existing catalog.

Sohovi validates your dataset before it enters the warehouse — catching format errors, nulls, and duplicates at the source.

Run a monthly duplicate check: A COUNTIF or SQL query against your product table takes 2 minutes and catches problems early.

Frequently Asked Questions

How common are duplicate SKUs in e-commerce stores?

Very common. Stores that have been operating for 3+ years, migrated platforms, or onboarded multiple team members without a SKU governance policy almost always have some duplicates.

What if my warehouse already shipped using a duplicate SKU?

Don't change historical records. Change the SKU going forward and add a note in your product record documenting the old SKU and when it changed. For accounting reconciliation, the audit trail is critical.

Can I automate SKU uniqueness checks?

Yes. Most e-commerce platforms enforce uniqueness at the platform level (Shopify will reject a duplicate SKU on import). If yours doesn't, a nightly SQL query on your product table or a Zapier automation can flag new duplicates.

Selva Santosh

Data quality, for people who ship

Selva writes practical guides on data quality, profiling, and governance to help teams ship better data.

Start for free

Stop guessing. Start knowing your data quality.

Sohovi profiles your datasets in minutes — surfacing completeness gaps, type mismatches, and duplicate patterns before they reach production.

No credit card required · Free forever plan