Identifying Rn-A1 Or Rn-A3

Can anybody tell me how to tell the difference between an RN-A1 black printed light and RN-A3 printed in gray?

Image below:

Hi, I do not know, other than one is black and one is gray.

What I'm really interested in is the marks in the right "S" and "2"? Do you know if these are one off, or does it show on all of these issues?

Stampmaster

Stamp master - There are several constant varieties of the A die. These were often set up to print several receipts at a time and then the receipts were cut apart.

1typesetter - As a cut square, there is probably no reliable way. Your image looks like the gray and not a lite printed black, but scans I am aware can be deceptive. To the best of my knowledge there is only one recorded user of the gray. Quite a few blacks were recorded in the Castenholz Field Guide for New York.