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Not hallmarks, just maker's marks. We have seen that particular set often on the forum, but to my knowledge that set of marks still remains unidentified. There were some thoughts in the past that maybe there was a connection with the Spanish firm Meneses, but nothing conclusive so far.
The marks have also been noted accompanied with a stick-on label of Eton
Silver Company, Glendale, New York were noted as importers, active from the 1960's to, at least, the mid 1970's.