Hello,
Thanks for your giveaway. There must be some bug. When I try to redeem the key, it shows I already have this game in my steam account (actually I don't), so I cannot redeem the key. I think you need to inform steamgifts.com to delete this giveaway by clicking "support" and creating a support ticket.
Sorry for the inconvenience that may cause.

Hello Floreo,
I have contacted the support team. Sadly,they said the giveaway cannot be rerolled due to incorrect information being selected when the giveaway was made. Therefore, please delete the giveaway instead.