Stocard usually tries to digitize your loyalty cards by using the same barcode format that is used on your plastic card. For 2D barcodes (e.g. QR codes) the barcode in Stocard might look slightly different but has the same information than the one on your plastic card.
If you have the feeling that the barcode in Stocard is not correct (and/or is not working in the store), please send us an email at firstname.lastname@example.org and attach a screenshot of your card in Stocard as well as a picture of the barcode on your plastic card. We will then check whether your card was digitized properly.