What does this overmintmark mean.... guessing here.. that the mint mark is larger than normal?? Here is the Quote from gentleman.... "For those collectors who wish to expand their collections to include some of the more difficult, and more expensive coins in the series, look for the overmintmarks such as: the 1949-D/S, 1954-S/D, 1955-D/S, and the overdate of the 1943/2-P."
I hope some more experienced collectors chime in, but I think thats when they take a die from the previous year, and stamp the new date on it.
That means the date on the die was changed. Rather than recycle the coin, they re-strike it with the new date over the old one and you can see traces of the 2 under the 3.
Mint marks were punched into dies by hand. Occassionally some marks were re-punched. So there are D marks punched after the S and vice versa. Some of these are really rare and collectible.