According to what I researched on this coin is that the FG is the key marker, it is what has been doubled. The other markers for this coin are in the lettering on the front, the lettering in America and the bottomof the T in states( the way it has been kinda sliced off on the end
Your pic of the designers initials isn't the greatest but you should see a definite extra top bar of the F above it. http://www.coppercoins.com/lincoln/diestate.php?date=1968&die_id=1968d1dr001&die_state=mds
After looking at the CopperCoins photo's, I can state, without a doubt in my mind, that this is NOT a DDR coin.