> By default, we use the manufacturer barcode to track eligible inventory throughout the fulfillment process, unless you change your barcode setting or your product is not eligible. When more than one seller has inventory with the same manufacturer barcode, we may fulfill orders with the inventory that’s closest to the buyer, to facilitate faster delivery
https://sellercentral.amazon.com/help/hub/reference/external...
> By default, we use the manufacturer barcode to track eligible inventory throughout the fulfillment process, unless you change your barcode setting or your product is not eligible. When more than one seller has inventory with the same manufacturer barcode, we may fulfill orders with the inventory that’s closest to the buyer, to facilitate faster delivery