Femaru P37 mag question

[Rmasters3]

I have a jhv 41 series, 7.65/.32acp with two mags. Both mags are marked "P. Mod. 37". One has a serial number stamped (it doesn't match the gun) the other has no number & no evidence of a number having been removed.

The gun's serial numbers all match and indicate early production of the Luftwaffe order, 1941 based on the numbers I have seen.

I also have a .380, M37 also made about 1941, and that mag is marked differently.

My question: why does one mag for the P37 have a serial number and the other is unmarked?

[32 Magnum]

From what I've seen, over the years - many of the European handguns were fitted at the factory with one magazine - that mag was numbered to the gun (sometimes two mags were fitted) - any spare mags were NOT numbered and were picked-up sometime along the way. If the un-numbered mag works with your gun, no problem.