Hi everyone I recently discovered this interesting mintmark on a
1964-D quarter. I am unsure if it is a true RPM,
Machine Doubling, or a combination. There appears to be the outline of a large D northeast of the main mark, with a smaller doubling east of the D. I think it looks pretty cool.
Here are the pictures taken with an iPhone through a 60x microscope. I took multiple angles to move the light glare around. To me, the shadows suggest multiple levels to the mintmark.

