Send HB link to winner, but he told me that gift was already used. What should i do now?

Well if you're 100% sure it wasn't used beforehand than well check their Steam Profile. It might sound mean, but what if the user redeemed it and said they didn't only to try to get a 2nd copy to trade away.

If not than let the winner mark the game as "not received."

If the you checked the link before and it didnt say that, then he activated the game on his main or alternate account.

They could just be total assholes and gifted their friend the copy, trying to get an extra one out of you. Not much you could do in this situation except to deliver another copy.

If you're sure that it wasn't used before, I wouldn't provide another copy - I know that the feedback then will be "not received" but personally I wouldn't want to go buy and then gift something to a frickin' thief and liar. Just my personal opinion

Contact Humble Bundle, tell them you had unused steam-key from humble so you sent gift to friend, but turns out key was used already. I wouldn't mention giveaways or steamgifts :P

Had similar issue, Humble Bundle Page told me I had unused Terraria key, I gifted it to friend, he says "key was already used". So I talked with Humble Support, gave info they needed (payment confirmation). Turned out key was actually used (by me) and it was Humble's site issue which showed it as unused. They deactivated my game on Steam and friend could use his gift.

Check first you didn't send the same link to multiple people.

I record myself doing the giveaway sending process when doing public giveaways, well that's probably a long long time ago.

I vote potatoes

I recommend not sending anything more, these are scammers running their scam.

Blacklist, and then explain to support that the gift was legit.

it ithe game is extremely cheap (like 5-6 refined) i would just buy another key from someone and give it to him, just to avoid wasting time.

Well unless you can prove that they somehow where trying to scam there is little you can do..

I mean you can either buy another gift and send it to them and hope they do not pull the same thing or just ignore them and lose a slot.

They may or may not be being dishonest i can not say on the matter,i am just saying this all works on the honor system but as such you will always find a few who are not so honest and this may one of those times.

I do miss the old humble links that show what account the key was redeemed to,though the keys are nice and quick so i guess we have to give up something to get direct keys.

Anyhow sorry your having this issue but i hope you do not let one bad GA get to you,thanks for all you have given.Anyhow good luck with the issue at hand

The humble site has a bad habit of not marking keys used... Like, you dispense the key and refresh the page, and it will revert to being hidden. I often find myself double checking :x

It's probably someone saying it's not used to try to get you to send them another copy after giving it away to someone else. Humble Bundle is reliable, so there's no chance they got a bad key. Let them mark as received, send screenshots to support, and report the user.

This is one of biggest reason I don't want to send or make GAs in this site. Far too many idiots out there to risk my reputation.

If Support lets this slide and sides with the 'winner', although I do believe TC is honest, then there'll be a floodgate of win scam.

I wouldn't assume someone is scamming you. I won a giveaway for Giana Sisters: Twisted Dreams, and I had the same problem. I claimed the page, but the key was already used. I literally tried to use the key seconds after getting the link. There was no way someone else used it in that time. I would ask support which Steam account used the key.

Just check his steam and see if he got the said game on his account, if noit, roll another link to him, maybe other game you hae, if he have the game, you can reroll and say he alread got the game.

If you know for sure it wasn't used, I'd report him on SteamRep and check his history for any previous bad dealings that help support your position. Perhaps ask giveaway creators whom he'd won from before and see if he does this thing all the time. I think SteamGifts should have a warning system in place where giveaway creators can flag a user if they believe something fishy is going on and with enough flags the user is suspended/banned for whatever duration/forever.

You can also pressure him and let him know that you know he's lying and you'll be reporting and blacklisting him -- that can turn around some scammers.

Looks like it's real HB problem -- now 2 gift links doesn't work.

I decided to bought 2 games and give it to winners.