On some 1984-dated 1 Peso coins, the engraver's initials "ra" (Rodolfo Alvarado) appear on the reverse under the lapel area, near the neck of the military coat of Morelos. After discovery & some subsequent criticism, Rudy's initials were removed and all future minting of the coin reflects a blank, polished, area on later coins.

Reminds me of our 1909-S V.D.B. Lincoln Cent drama.  I wonder if Rodolfo's Peso will be as scarce & dear to Mexican collectors,

as our Lincoln cent (V.D.B) came to be among American coin collectors? Because of widespread criticism, only a small number of 1909-S VDB pennies were ever minted. The criticism was over Victor's initials, seen on the reverse bottom of the cent. 

My camera, unfortunately, isn't able to share the tiny details, but, they're there!  

Shipped with insurance and tracking.

Thanks for looking!