This is such a common issue that I would be more surprised if you did find examples from the same dies. If there were several from the same dies, which also shared the same wear pattern and shape then we could easily conclude it to be a cast. At the moment I am edging towards a corroded and repatinated original. But I will now keep my eyes open for a match to prove that conclusion incorrect.
Style (especially in the lettering style), and fabric leave me with suspicious doubts.
The texture of the surfaces remind me of pressure die casting, similar to zinc alloy diecast toy cars. Very constant thickness is not indicative of ancient manufacture.
I agree that it is possible that the coins have had their appearance treated to make them appear as genuine.
As far a s provenance is concerned, seller has said where they came from, but I would like independent proof of that, not just the seller's say so. Unfortunately, this sort of independent proof is often not available, even with genuine coins, for many different sorts of reasons.
Although I cannot completely dismiss them as fake, my motivation would be not to buy. There are lots of other nice Probus coins are out there for your consideration, anyway.