Hey, I am the winner, but I get a "product already owned" error, even though I do not own this DLC yet.
Are you sure it is exactly this DLC?

Well, I am gonna leave another comment, since I didn't hear from you yet.
Please read my above comment

Hey there! You won a prize in my Halloween event (Back to the Darkness From Whence Ye Came!)! However, I don't see a screen shot from you anywhere proving that you properly beat the game (see the instructions in the original post). If I just missed it, then apologies. There are a lot of pages of comments to look through. :)

Please provide a link to a screen shot proving your win. I'm giving everyone who hasn't already posted proof of their win 48 hours, and then after that, I'm asking for rerolls.

Congrats, and I'm looking forward to seeing your winning proof! Cheers!