Neat and baffling! As clean-cut a card effect as you will ever see anywhere!
Two cards are selected by cutting the deck in two piles. Four double-blank cards are shown and the packet is waved over the first pile. A card appears between the blank cards, say the AS. When the top card of the pile is turned over it is seen to be the AS. The same thing is repeated with the second pile: The duplicate of the top card (say the 3H) appears between the blank cards. Now you show that you have the AS printed on one card and the 3H printed on another. Suddenly, the two cards BLEND together and you now have a double-faced card that can be examined (as are the other cards).
Supplied with special cards (use any deck).