1942 D Mercury RPM Or DD Or?

The question I always want to answer on a question if it is a RPM or not is this: "Does it look like part of the mintmark punch?" Take a look at this page and see what I'm talking about:
http://www.varietyvista.com/06%20Me...%201942D.htm
If it doesn't follow the design of the punch, I tend to disregard them as being a RPM. I've only found one RPM on Mercury dimes. But I saved it anyway:

For the longest time I didn't see a listing for it, but now it has one. RPM-003

I have been out for a while, due to health issue, recovering and just reading from time to time in the forum.

@radatat,

I would say this is relatively common and seen quite a few of these anomaly, its more like a combination of circulation wear and Machine Doubling.

Sort of looks like someone pasted one D on top of another one.
But probably just MD.