SHORT ANSWER
A duplicate can mean two different things.
The SKU may appear twice inside your CSV, or one row may match a product already in WooCommerce. The file alone can reveal the first case; only a store export and import log can confirm the second. WooCommerce uses IDs or SKUs to match existing products when “Update existing products” is selected.
Save the import log, back up the store, and keep an untouched export. Never change a production SKU merely to silence an error: orders, inventory feeds, and integrations may rely on it.
If the file is rejected before rows are processed, start with the broader WooCommerce CSV error checklist.
FOUR CASES
Match the fix to the row that failed.
The SKU already exists in this store
A create import does not become an update just because its CSV row has a matching SKU.
Next step: If you intend to change that product, export its current row and review the Update existing products option. If it is genuinely a new product, give it a unique SKU instead.
Two rows in the file use the same SKU
The core importer needs a unique product or variation identity; duplicate SKUs in one file need a human decision.
Next step: Check whether the rows describe the same item, separate products, or variations. Keep the intended identity; do not blindly append a number to every duplicate.
Update mode skips an unmatched row
For existing products, WooCommerce matches the CSV by product ID or SKU. Unmatched product rows are normally skipped during an update.
Next step: Compare the row with a fresh export from this store. Correct the intended ID or SKU, or import the truly new product separately in create mode.
A variation is skipped or targets the wrong parent
A variation needs its own identifier and a Parent value that resolves to the intended variable product.
Next step: Check the parent SKU or id:123 reference, each variation SKU, and the attribute values. The behavior of new variation rows in update mode depends on the WooCommerce version and row conditions.
TOOL BOUNDARY
A local check cannot see your store.
- Repeated SKUs within the CSV
- Missing identifiers and common row-shape problems
- Existing IDs and SKUs in this store
- Import mode, column mapping, and skipped-row log
- Variation creation behavior for your installed version
Our free scan stays in your browser. It does not connect to WooCommerce or decide which product an existing SKU should update.
SAFE RETEST
Prove the mode and identity with a small batch.
- 01Preserve
Back up the site; save the log and a fresh product export.
- 02Classify
Separate file-internal duplicates from SKUs already in the store.
- 03Choose
Confirm create versus update and review the column mapping.
- 04Test
Import one or two representative rows on staging when possible.
- 05Verify
Check the product, variation, price, stock, and import log before scaling up.
PRIMARY SOURCES