Fairly common to find as there 29 different listed RPM's for 1953 D. Yours both appear to be RPM-001, with ref to the position of the MM
We didn't know that when we were young (in the 50's). Variations were not part of the routine and details of them were not available. I am finding lots of neat stuff in my accumulations.
It's like looking through old stuff with new eyes. and you are discovering pieces anew that gave you great pleasure when acquiring them that you probably haven't looked at in some time
I joined CT because I was sorting my 70-year accumulation and was finding stuff I was not certain of. If anyone is interested, I posted my effort about 3 years ago. https://www.cointalk.com/threads/sorting-my-70-year-accumulation.330231/