Definition: An overpunched mintmark (OPM, or OMM for over mintmark) is a coin specimen that exhibits more than one different mintmark, one punched on top of the other. For example, a coin with an S mintmark, for San Francisco, might also have a D (for Denver) punched on top of the S, due to human error at the mint. Until 1990, each coin die was individually punched with the necessary mintmark, and sometimes the mint workers made mistakes in punching which didn't get caught before coins were produced with the affected dies. Coins with overpunched mintmarks are extremely collectible.
See also: Repunched mintmarks (RPMs)
See also: Repunched mintmarks (RPMs)
Examples: The difference between an overpunched mintmark variety and a repunched mintmark is that the overpunched mintmark involves two different mintmark letters, whereas the repunched mintmark involves just one mintmark letter punched two or more times.
