Every barcode of a variant, each with its type

The Variants table now has a Barcode column with each variant's primary code and how many more it has. Edit barcodes lists every code of the variant with its type — EAN, UPC, GTIN, ISBN, ASIN, Custom or your company's own code types — each checked against its format. The first one is the primary.

Code types are managed in Settings › Catalog data. Imports rename a SKU only when the file says so, with a previous SKU column, and stop any row whose barcode or SKU already belongs to another product, so codes are never silently mixed up.