See what you mean. The mass coin is different and isn't a match. I actually bid on it but it went above my budget. If its a fake its a worrying development.
Why pick an obscurely spelled moneyer and mint if you were going to fake a coin. You would also need a good example coin to make a copy and the Osbei in Mass is not clearer enough to do that and I've not seen any others like it elsewhere either.
The seller was selling other coins also none of which gave me any red flags , his feed back seems okay also especially in regards to coins. Nothing really jumps out about him.
Its rare to see a 1a5 in such a grade that much i agree. Thats all i felt uneasy about really when i saw it.