1963-D Nickel What Do You Think, A New RPM? Or Not An RPM?

I don't think any of them look like RPM's but what do I know. Yours looks like deterioration and MD and Brians looks like die chips.

looks like DDD with radial flow lines

I don't think it's an RPM. Probably just Die Deterioration.

Well before this topic I opened Two BU rolls and in one of the rolls there were 32 of the above mint marks, obviously struck by the same Die.
And in the other roll there were 21 of the below MM example.

The coins are all in amazing grade most of them with bluish purple toning.
It was fun opening these rolls after 63 Yrs. I am checking on a few of these coins under the scope I suspect there might be a doubled die on the 3 of the date if they are I'll post it for you.