I saw this on eBay, generically described as a 'Roman Alexandrian Drachm' or some such. Not recognizing the reverse, and seeing that it was pretty cheap, I bought it. It came with a tag from Littleton, giving a generic description of Alexandria and Trajan. It's hard to photograph due to the wear, but shows up better in hand. To my eyes it looks to be this coin, RPC 4411, which shows three specimens in museum collections. I wasn't able to find any on WildWinds or recent sales, although I don't have full access to CoinArchives or ACSearch. It's rough, but am I correct in assuming this is probably a pretty rare issue?