The KM catalog groups these anonymous 6 bagattini coins into 4 subtypes (#6, #77, #218, #367) spread across about 75 years, based on certain features including the legend, mintmaster initials, and the weight.
Specialty Italian catalogs may do it differently .
I cannot find another example with the legend SANCTVS MARCVS VENETV, so it must be uncommon.
Possibly @cippirimerlo has access to a good reference for Venice and can make a determination on whether to submit it as a new type..