I don't think it's machine doubling there seems to be three individual punches. I would say if you can get better pics we could judge better don;t rule this one out yet. JC
I'm leaning more towards Machine doubling... Since the MM looks sheared and leaving the "doubling" flat...
Since the mint mark's effect is rather large, if it was machine doubling, I would expect to see at least a small amount of machine doubling at the bottom of the "9" or "7". Perhaps you might find a listing for a RPM in this direction for a small date 1974 D, but it doesn't seem to be a prominent one. Jim
I could be wrong on this, but the first thing that came to my mind was post mint damage? I could be wrong, but that is what I'm leaning towards. =/ Phoenix