I bought a Steam key for some game, but when I add the key to Steam, I'm told that I already own the game. As I think the seller (not Steam itself) sold me a key for the wrong game, I'd like to get some proof of that. How can I see details corresponding to the key?
The game I wanted to buy is "Prey" released in 2006, but I think I got "Prey" released in 2017 (which I already own, from a previous failed attempt to buy the 2006 game). However, without some kind of proof that the key corresponds to "Prey" 2017, it's hard to get a refund.