Double Date marking question

[southriv]

I'm still in the early learning stage, but this mark on the back of the frame has me a bit confused. This double date is all matching including the grips (but not, unfortunately, the mag) and correct proofs. From what I have gleaned from the reading material recommended, I believe the 1920 on this one is a property stamp and this is not an arsenal rebuild.

I have seen import marks in this location , but not this. The script looks a bit old-fashioned. Any ideas would be appreciated & I can post more pics. If a moderator feels this would be better served in the New Collectors forum, feel free to move it.

Bob