Let me see if I can walk you through this. First off, what is it you see that makes you think this is an RPM to begin with? I will assume(may get me in trouble...LOL!) it is the shadowed areas on the northern edges of the curves, correct? Now, lets compare yours to the RPM-001 on varietyvista.com


Oops, not in the right spot, see it? a slight shift to the right on yours. Means it can't be this one. Secondly, compare the edges on the northern curves. On yours, there is a 45 degree flat angle causing that shadow, on the example pis, there is a definite flat image of something else.
Now is this another RPM? I see no indication on yours of split serifs or a dividing line on the MM. Hope this helps...
Oh, final thought...that "glob" inside the lower half, there is debate if this is a damaged punch or something else, shows on many dies?