"M" Stamp near Whiting hallmark

Aloha,
I have multiple Whiting King Albert flatware pieces with an “M” stamped in the vicinity of the hallmark. It doesn’t appear to be a datemark. Anyone know the meaning of this?
Mahalo,
PoiDogPhil

Hello, the photo didn’t come. No photo, no help :joy: :joy: :joy: joke

Something like that?


Yes, like the back side.