Found this in roll this morning. I believe this is listed on Variety Vista as 1963-D RPM-001 and on copper coins as 1963D-1mm-01. Just thought I'd share.
I believe this is a good example of an RPM that expresses itself more fully in later die states. The pic you show is from VV, and shows Stage A, correct? The coin the OP shows is probably Stage C or D, and the die has worn, while the secondary mintmark has "relaxed" and has become more visible than it was in Stage A. There are many RPMs that exhibit this behavior, ie becoming more prominent as the die wears.
The markers appear to line up with VV1963D-RPM-001 Stage C. No Die Chip On Right Cornice, Die Chip On Left Base Tip and No Die Crack On Column #1
