Thank you @Herodotus. Here is the link to another thread relating to countermarked Claudian coins that I initiated a little earlier than the one you cite - I was absent from Coin Talk during that period: Claudius countermarked coinage (updated)
So I see it is an eBay sale coin based on the posts of @Herodotus. I am still bothered about the wide flan thickness depicted in one of the photos you posted and the quoted weight. If I were contemplating purchasing this coin (which I am not) I would insist on a guarantee of that weight (which is in the range listed in BMCRE, volume I, Rome, Claudius, No. 222) and ask for more information relating to the flan thickness.