Help With US #77 - Reperf?

I picked up this #77 a while back and looking at it now, Im wondering if it was reperfed at the right? Looks like it could have also maybe been trimmed away from a pair?






Thanks!

The right side needs to be carefully checked; it may or may not be reperforated. Can't really tell from a scan.

The left side perfs don't quite line up with the right perfs in photoshop so it is possibly reperfed. I note a small round stain in the lower left corner (easily seen from the back).

These stamps were perforated on a single line perforator. A woman aligned single sheets of stamps on the perforator tabletop and the sheets were pulled into the perforator by rolls. This pulling action imprinted a "pull direction" on the perforation holes. As a result, they are not round but slightly elliptical.

If you look at the back of the stamp:
At right, all (except the two top ones) the perf holes appear to be slightly elongated to the bottom left. This points to an upward pull direction of the sheet.
At left, many (some are perfectly round) perf holes appear to be slightly elongated to the bottom right. This points to a downward pull direction of the sheet.

This is impossible, the pull direction must be identical on both sides as all columns were obviously perforated within the same cycle.
Since there are more "round" perf holes on the left (looking at the back of the stamp), my guess would be:

1. The right side (seen from the front) is reperfed
2. A few perf holes might have been "prettyfied" on the left side.

Thank you for confirming my suspicions, and drkohler - thank you for that lovely explanation of how the stamps were perforated!