Grease filled die, not all that common where a complete digit is filled in with grease, I have various 2 cent pieces that show this characteristic. Neat a worth maybe a small premium to a variety collector.

In this photo the 1 in the date shows up more than it does in hand, due to my lighting. I also have a bunch with all or partial letters missing on the reverse.
"Buy the Book Before You Buy the Coin" - Aaron R. Feldman - "And read it" - Me 2013!
ANA Life Member #3288 in good standing since 1981, ANS, Early American Coppers Member (EAC), Colonial Coin Collectors Club member (C4), Conder Token Collector Club member (CTCC), Civil War Token Society (CWTS) member, Liberty Seated Collectors Club (LSCC) & Numismatic Bibliomania Society member (NBS), USMex, Member in good standing, 2¢ variety collector.
See my want page:
http://goccf.com/t/140440