Listings can be created with the same barcode with different ASIN's assigned. The Amazon Auto Pricing Software should be installed and running to automatically set ASIN's for barcodes.
If the ASIN suggested by SellerExpress does not match the required listing on Amazon it is recommended to manually set this via the Product Details Screen under Marketplace Tab (Listing ID).
Assign ASIN's Manually: Click here.
Auto Pricing Tool Running: Click here.