[Sirrotica]

FWIW, just my opinion, and because I did work in a foundry for about 6 months about 55 years ago. It seems to me that these heads have a raised portion where the insignias are. I would surmise that some union worker, that was bored, used a penny to make the insignias on and glued to to the pattern before the casting was made. It may have been patterns that were scheduled to be retired, or reworked.

The reason I say that, is because a penny is made of copper, and very easy to work with hand tools because of the malleability of that particular metal. My money is on a pattern modification, rather than making the design on an already cast head. I however may be totally wrong, wouldn't be the first time.
It just seems to me from the pictures that the portion is raised above what a stock head would have material in that area.......

Just for grins, I'd try laying a penny over the insignia to see if my theory has any merit.

Thanks to the OP for making the board aware of this abnormality, that some frustrated artist has made.