My understanding that any shop that makes its own rings can add stampings, and with no central repository of all shops ever (as I understand it) it is difficult to work out the history on a piece.
You could try putting some tracing paper over it and rubbing a pencil over it, to bring out the design and 'lose' the background, which might make it clearer?
Over my long life I've bought many hallmarked sterling silver items at garage sales.
Now I can figure out their provenance.
Gotta love garage sales for bargains on treasures.
Old cast iron pans with decades-old seasoning in perfect condition is another treasure I keep and eye out for.