~~~ in a case such as this (font; size, slant) since neither changes the size, shape, color or the most important factor; the monogram for ID... and, the results may simply be more than one engraver on the run and no way of knowing without seeing a pattern (many more pieces).
This example is mine...

ChipGuide image
...and this example is on auction.

The engraved serial number doesn't change or affect the ID of the piece and, what if there is an inventory large enough to entail 20 differnt known serial numbers -- do we include them all... Yes, a little far fetched but, ID is still our main goal, or not...?