Rolex 16610 1993 backcase engraving Problem

[costeadrian]

Hello all! I came across this rolex 16610 serial S from 1993, everything is good with the watch, movement, dial, engravings and the bracelet. I notice the engraving of the caseback is not normal. The little oval “rolexsa” stamp is missing, and i have the PATENDED writing that i see just on on older models of submariner’s and others.
Is this normal? Did you see this on other 16610 this caseback? Thanks