Lab Case · Blocked

Two CSV columns with the same header name

The rows are rectangular, but downstream field mapping becomes ambiguous when two columns share an identical name.

Reproducible fixture
Issue: duplicate headerOutcome: repair blockedRows: rectangular

Fixture

name,price,price
Blue Shirt,19.99,USD
Red Shirt,24.50,USD

Why this is structurally risky

The table has three values per row, so column count alone looks healthy. The problem is the header: both the second and third columns are named price. A destination that maps values by header name cannot reliably distinguish a numeric price from the currency text in this fixture.

Why automatic renaming would be guessing

Renaming the third column to currency seems reasonable to a person reading these two rows, but the CSV file itself does not define that meaning. Another dataset could use the second price as wholesale price, compare-at price, tax-inclusive price, or something else.

Upload the fixture

The checker should report the repeated header name.

Check the source schema

Find the real field names in the exporting system or import template.

Rename intentionally

Use the exact destination field name rather than an inferred label.

Run preflight again

Confirm every non-empty header is unique.

Decision: duplicate headers are diagnosed, not auto-renamed.