Interesting piece. Searching online auction archives, I only find one other attributed example of a portrait 8R being struck over an earlier Sombrerete piece.
https://auctions.stacksbowers.com/l...8-reales-18-
Note that this piece was struck over the Sombrerete raised stamp style, rather than the recessed style like the coin in question. Stack's Ponterio calls the later (poor) portrait strike Durango, but it COULD be Chihuahua.

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Then this one... not over a Sombrerete host, but instead an MVA 1812 stamp (presumably on a cast Chihuahua 8R). Serves to illustrate Chihuahua struck over a recessed counterstamp:
https://www.acsearch.info/search.html?id=2708144
https://auctions.stacksbowers.com/l...8-reales-18-
Note that this piece was struck over the Sombrerete raised stamp style, rather than the recessed style like the coin in question. Stack's Ponterio calls the later (poor) portrait strike Durango, but it COULD be Chihuahua.

----------------------
Then this one... not over a Sombrerete host, but instead an MVA 1812 stamp (presumably on a cast Chihuahua 8R). Serves to illustrate Chihuahua struck over a recessed counterstamp:
https://www.acsearch.info/search.html?id=2708144



















