Thanks!

View attached image.

"The product code you've entered has already been activated by a different Steam account. This code cannot be used again. Please contact the retailer or online seller where the code was purchased for assistance."

EDIT: all sorted and he was quick about it as well

I also got a duplicate code.

Edit: giveaway creator contacted me, explained the situation and provided a working key. Received!

Those keys were from OtakuBundle.com. I bought 10 copies of their Bundle #17 with that game. I still have 3 of them, so I'm adding you guys on Steam and we'll try the other ones.

thanks