Unfortunately it seems all of my latest giveaways contained duplicate keys. Since they were all old Humble Bundle keys I had laying around I don't know what happened. Maybe they expire after a certain amount of time? Either way I apologize for this poop fest and I'm currently manually buying new keys for all winners. New keys will be resent ASAP via the regular steamgifts.com key delivery system. I'm pasting this comment in all affected giveaways.

Edit: new, fresh key sent.

Edit 2: After going through my Humble Bundle UI more thoroughly I realized I was completely to blame. I was literally sending out keys I, myself, had redeemed at one point. I somehow managed to mix up used keys with unused keys. Humble Bundle is blameless!