Stocard usually tries to digitize your loyalty cards by using the same barcode format that is also used on your plastic card. For 2D barcodes (e.g. QR codes) though the barcode in Stocard might look slightly different but contains the same information than the one on your plastic card.
If you have the feeling that the barcode in Stocard might not be correct (and/or is not working in the store), please send us an email at email@example.com or 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. Our customer support team will then check whether your barcode was converted properly.