It says its "Duplicate Product Code" :(

Are you sure about this, I get this key and some other from a Christmas Giveaway a few days ago and all other key I used by myself worked fine. Here is a screenshot from the mail: https://www2.pic-upload.de/img/34451556/SG.png

https://gyazo.com/6bf92467e91bfe46f9dd03f20751926c Idk, it doesnt work for me...

I regrouped the keys i got from the giveaway and i found the 3 keys from that game. 2 i used by myself and 1 musst to be unsed, perhaps i took the wrong key, pls add me on steam or anywhere else so i can give you the other keys.