Double-sided coins are coins that go through a process of melding together two heads or two tails of the same type of coin. The result is a coin that has the same image on the obverse and reverse sides.
Contrary to popular belief, double-sided coins are not worth much to collectors. A whole industry manufactures double-sided coins for use in pranks and in magic tricks. It is impossible for the U.S. Mint to strike double-sided coins, as the dies used to impress coins only fit into the manufacturing shafts one way. Any coin found in circulation with double sides is the result of someone accidentally spending a novelty coin.