You cannot buy a new key on the same account. I went through support and the only way you can play Overwatch again is to purchase it on a separate account.
Me and support just now. you: Hey there, I'm a Cunt that got banned for cheating in overwatch. you: Wanted to try it, Got scarred for it. Thats fair rules are rules but! you: Am i allowed to buy the game on another account and play the game you: Or are you really banning hwid and ips. you: Because if you are im fuck'd Thrakdrar: Wow, that's quite an intro. you: I know, I rather give you the full details then beat around the bush for the next 20 mins saying it was my friend. Thrakdrar: Nah, that's understandable. I think I prefer the details now. Thrakdrar: You're definitely allowed to buy the game on another Battle.net account. you: Will that get banned? Because so many people are reporting that they got the game after they got banned and even without any 3rd partiy programs they still got banned Thrakdrar: It should only be banned if you continue cheating on that account. you: So if do a full reinstall of my pc, remove all traces and buy a new account it will be fine. Thrakdrar: I'm not precisely sure, but I know that the Overwatch ban is account-wide, which means that even if you detach the old Overwatch and buy a new one you'll still be banned. you: Fair enough. I was just scared to buy it on another account if im not allowed on the game anymore its fine, i just didnt wanted to spend money on it then. Thrakdrar: You should be fine if you buy it on another account, so long as you don't cheat on that one as well. Thrakdrar: Glad to give you the good news, heh. ps. Never again will i use this "Tyrant" thing have fun i have requested my refund for tyrant and im out.
So always you can check overwatch accounts on sites like mmo auctions https://mmoauctions.com/overwatch/accounts