This LMC looks to have a gouge or other anomaly on the front of the jacket just below the tie. I'm thinking gouge because the rest of the surfaces are considerable heavy with die scratches.
I see it to the left of the tie. I also see a possible gouge above the tie to the side of the collar.
Witness mark from the reverse die. Also a bit of a heavy engraving tool touch up. Pretty normal stuff.
Thanks for all the comments. I think what I am seeing now is an over-polished die. It looks like much of the front of the coat has been removed. More comments appreciated.
Looking at more 1964 D LMC's I am now leaning towards die crack/chip. Here are two more with the same condition.
Thanks for putting that photo with the red arrow up. I couldn't see anything you were seeing until that, but then I can't see all that well anyway. LOL