All of mine only have the serial no. That's interesting.

Most of the hammers I've seen only have the serial numbers too.

Here is another set with a 2 stamp. This was a set that Patrick Lein sold a while back.

Interesting... 19595 and 21597 are 1880 and 1881 guns. I wonder if the additional stamp, in the case of these two serial numbers a "2", was something Parker Bros did particular to a small range of years or serial numbers.

Does anyone else have hammers with additional stamps besides the serial number?

That's a possibility Dean, but here here's another set from 1881 without the "2".

So much for that theory.......

The 2 on the hammer appears to be stamped with the same punch used in the serial no. I thought it may have put on when they were cast for some reason. But apparently not.

Maybe Parker Bros. Had some intellectually challenged assemblers and needed them to know that there should be two (2) hammers.

I could not help myself.......

One part curiosity, one part boredom,and one part post Addieville blues, I decided to have a look at the back of my hammers.
One 12, and three sixteens, and no stamped number 2. However, I found something that sort of surprised me; no SN on one of the two one my grade 2 16ga. All appearances are they are original, and match each other. Huh!