I found several times makermarks with the initials of the city before of the number and not behind as prescribed.

I also tried to find the reason of this fact by writing to companies still operating, but they never have been able to give sure answers: these events occurred more than 60 years ago.
Probably some jewelers have made punches for themselves while waiting for the official ones from Rome.
Also the 750 in free field and not included in a lozenge, as prescribed, is not uncommon.
This evidence, however, argue in favor of VA 37 (FANTI Giacomo , Via Matteotti 22 Gallarate Varese) which had the identification number around 1948, shortly after the end of the WW2, rather than 87 VA (SOMMARUGA Luigi Via Roma, 11 Cassano MAGNAGO Varese)which had the identification number around 1955.
Regards
Amena