1956 Lincoln Cent with Repunched Mint Mark - NGC Certified MS-65 Red FS-508 (022)
Instead of a "Doubled D" Mint Mark, this Lincoln Cent has two! Under magnification a second "ghost" D is visible under the mint mark. Especially visible when the coins is held at a certain angle. Two D's for the price of one with this one!
This coin is considered to be one of the CONECA Top 100 errors. CONECA stands for Combined Organizations of Numismatic Error Collectors of America.