A doubled die
coin is a coin that was struck from a die that had a partial or full doubled image on it. The doubling comes from mistakes in the die hubbing process, where more than one image is transferred from the hub to the coin die. The 1955 doubled die Lincoln Cent (see photo) is the classic example of a doubled die, and sparked the start of the error coin collecting hobby in the U.S. Although no other doubled die types exhibiting the remarkable degree of doubling seen on the 1955 cent have emerged from the U.S. Mint, noteworthy doubling has also been found on 1972 and 1995 Lincoln Cents.
See also: Mechanical Doubling
and Die Abrasion Doubling
Common Misspellings: double die
I check every single coin that comes into my hands to see if it is a doubled die