One of my keys didn't work in a giveaway, so I bought a new key for the GA winner.

I like muffins.

I'm sad to tell you but based on winner's profile he probably gave the key to somebody else and lied to you that the key was used already.

Still, you acted as an awesome guy, but I wouldn't believe the winner in that case.

Did they tell you the key didn't work? I've had people no activate my keys before. If they say it's not a valid key, check where you bought it from. Most recognized companies will revoke the key and give you a new (working) one. You didn't need to buy.

Edit: Oh, it's probably been there for a while, so it might be too late then. Anyway, you acted well, but if you checked the profile and it looked fishy, you should probably have taken the hit for it.

I had a similar problem with a key in my Nine & Forty Birthday adventure. However, despite having the game in my "not used keys" list I did notice my wife had the game in her library and she couldn't recall purchasing it so I'm pretty certain I'd given it to her and forgot to update my list.

Sadly I didn't have another spare key but as I didn't want to disappoint the winner I offered to give them a spare key for a game I had on their wishlist. I had to get special permission off SG support so they could change the GA game for me and they made it clear it was a one off change they would make for me and it was not to be repeated :)

Next time I'm afraid I'll just have to delete the GA (although I may still try and send them a different spare key I have via Steam)

It happens, sorry it happened to you.
I've received duped keys from a couple of different sites before (hell, received an entire bundle of dupes once).

Glad to see you handled it well and hope it doesn't happen again :)

I've only had a problem with one key so far and the user was completely trustworthy so I just took the hit and bought a new key.

Ok guys thanks for the input.