Just found Mexican 2 peso bimetallic coin which has inverted stainless steel outer ring with normal center. By this I mean that 'Estados Unidos Mexicanos" title is displayed on the same side with Edge ($2 is displayed), not on Obverse as any other coin. Would it be rare? Any clue?
For this to be a genuine error is impossible. Each half of the die simultaneously strikes both the center and outer ring designs.