Many stores print one receipt for the goods you bought (which is yours to keep) printed by the register, and two receipts for the card transaction (so one for both) printed by the card terminal. This is mostly for historical reasons due to how card transactions were introduced to German merchants. They have stuck to that and still design new so-called "hybrid" terminals which have a receipt printer and take the card in for the full length (so the flow for magstripe and chip transactions is exactly the same with no confusion even though magstripe basically only happens for foreign cards now).

Smarter merchants print muss less: Rewe, which is used in the example, doesn't print receipts at all unless specifically requested by the cashier and then only one which contains both the goods bought and the card transaction data for the customer. A merchant receipt is only printed in case a signature is required.

Probably Händlerbeleg (Merchant receipt), Kundenbeleg (Customer receipt) and then a normal Kassenbon (just the receipt with what you bought) but I have only seen the two customer ones in one.