I was checking out the Teletrade auction for tonight, first time I've seen an NGC mistake like this. The indicates it's twenty cent piece but the coin in the slab is 1876 CC dime
It seems these "clerical errors" are becoming more common place (probably because I never paid any attention to them, but they do appear quite often here on CT).
For what a mint state 20 center goes for, imagine your surprise when you opened the package if you bought this sight unseen.