Agreed, pictures aren't close/detailed enough. Also, from my experience, when you are seeing "doubling" on just the mint mark it is most likely either 1) damage, 2) MD, 3) an RPM - which is not actually doubling. Might I suggest that you bookmark this website: http://coppercoins.com/advsearch.php I use it every time I see something through my loupe that looks interesting.
Maybe http://coppercoins.com/lincoln/diestate.php?date=1968&die_id=1968d1mm001&die_state=mds But your's looks more like the "D" took a hit.