Card Swap (M12)

You show a face down packet of about a dozen cards. The spectator cuts the pile in half. They select a half and put them behind their back. You put the other half behind your back. You explain you that you will randomly remove one card from your packet and place it face down on the table without looking at it. You tell them to do the same. When those two cards are turned face up, they match! You explain that they must think that all of the cards must be the same. Turn them all over and indeed they are the same BUT, they are not the same card as yours or theirs!