1920-D Lincoln Cent - RPM? WRPM-001? Or . . . What?

This one has me puzzled. It is a generic solid G-4 1920-D Lincoln, but the lower serif on the mm appears to have a clear notch.

My first thought was John Wexler's 1920-D WRPM-001. It is close, but the mm location seems just a hair off. The mm on this one looks like it is very slightly north and east of the mm on WRPM-001. Unlike WRPM-001, this mm does not appear to be in a recessed area and does not appear to have the die gouge (or something) to the left of the mm that is in the Wexler photos. The WRPM-001 mm appears to be upright, while this mm appears to have a very slight NW tilt. There are no known die markers for the Wexler variety, so there isn't anything for comparison.

So . . . here are my questions:
1. Is there a notch on the lower serif?
2. If so, is this an RPM?
3. If it is an RPM, am I right that the mm is close, but not quite in the same location as WRPM-001?
4. So . . . is this a nothing, a WRPM-001, or a new RPM?

Here are the photos:

Date and mm, to help with mm position and comparison:



MM details: