A repunched mintmark
, or RPM
, is a coin that exhibits two or more images of the same mintmark, caused by errors in the punching of the mintmark onto the coin die (or very rarely, onto the hub.) Up until 1990, the U.S. Mint used to manually punch the mintmark into each individual coin die. Occasionally, due to human error, a die would get two or more punches of the same mintmark, sometimes in almost the same location, and sometimes at 90 or 180 degree rotations! Although the mint workers usually caught these defective dies before any coins were produced from them, on very occasions a die would strike coins with multiple impressions of the same mintmark letter. Such specimens are called repunched mintmarks, or RPMs. In general, they are very collectible.
See also: Overpunched Mintmark (aka OPM or OMM)
When I saw two Ds on the coin, very close to each other, in the spot where the mintmark should be, I realized that I was looking at my first example of a repunched mintmark