Thanks for reaching out! Unfortunately at this point, TradeGecko currently ties only 1 unique barcode to a variant.
It sounds like what you are looking for at the moment is serial tracking on the platform, something that we do not currently support on the platform.
One way to track these items as they come into the warehouse is to use a barcode scanner as you receive a purchase order. By using a barcode scanner, you should eliminate the possibility for error, and allow you to have one barcode per variant.
Please let us know if you have any other questions regarding this topic and we’d be happy to help!