Did Your Card Buy Someone Else's Groceries?

I bought groceries last week, exactly $10 worth of on-sale granola bars and Sobe drinks for a whopping total of $10. I used the self scan service, and walked out with my receipt and groceries. I was looking at my account balance to see what checks and debits had cleared, and I did not see my $10 amount, several days later (and this grocery store always posts on same or next day to my account). Well, in looking at the receipt - it was not my card that was charged, but an American Express card, which I do not have one of. Nor did I have any card ending in the last 4 digits of 8007 as was on the receipt. I went to the store and the management was baffled - perhaps the checkstand had held onto the previous card and paid for the purchase I made? They had not seen this happen before, and it had not happened to me, either, but the amount was correct, the items were correct, and the American Express pruchase was wrong. It was my receipt, with correct date and time and items, but no charge was made to my account. This type of situation may not be readily reported to a store - since most people tend to throw away receipts, or not look at them like I do. If they don't see a charge come through, they don't worry about it. If they see a receipt with a wrong card, most people would not report it since it won't show up on their card. So, who knows how often this might happen? Check your balances and keep your receipts - it's the only way to prove that your amounts match the amounts that come through as charges. If you get charged twice at the same store (and did not make 2 purchases) and have the correct receipt, perhaps a scanner held onto your card information and used it to buy for the next person in line? You can take your receipt in and let the store know the other charge must be wrong. This is the only way the store can start looking into the potential problem. Until then, no one knows if there is a problem.
http://doubleii.com/credit.html