Check this out. It's the first RPM I've ever found and I've been looking for a while. I can't find a match on coppercoins.com though. Anyone have a clue? It kinda looks like a D over D over D.
I think you are talking about a RePunched Mintmark (RPM). MM would just be a mintmark. I see what you are talking about. I'm no expert on RPMs but that certainly looks like it could be one. I don't see this particular one in my Cherrypicker's Guide.
Keep us posted if this is a known RPM. I know that The Cherrypicker's Guide does not include every RPM.
Coneca has 71 RMP's listed for this year and mm so it's gonna take me awhile but when I find a match I'll let you guys know which one it is.
Update Just an update: With a little help I have matched this RPM to 1961 D RPM-038. Just wanted to let you all know.