Unlisted 1986 D/D Mint Mark Variety?

Looks like a RPM to me.

what's MD?

Ah, another Padwan! MD my son, is Machine Doubling or Mechanical Damage. It is formed in the striking process whereas true Doubling is in the die making process. In the diagrams following you can see the differences, Mainly, devices are made smaller by MD and are larger when doubled.








While your coin on the MM may appear larger in size that "shelving" effect is the giveaway, you don't have doubling on date AND MM especially when movement on the devices are in same direction (see 69S example of MD).

Worn dies are a different animal entirely. Die wear/deterioration has to do with the metal movement outwards on the die face and then the polishing of it to remove damages and imperfections caused by pounding the **** out of it.







There, you have the load of it, tried to make it as simple as possible.