Perhaps not necessary to delete, no, but unfortunately, there is not a way I'm aware of to test the key without actually trying to activate it, which of course is no good for us here.

Ninja Edit
If the key turns out to not be valid for the full game, the winner should mark the game as "Not Received", or you can maybe work it out with them to provide a valid key, or to delete (see below).

Again, not that you need to delete at this point, but should you want to delete this or any giveaway in the future, you can click the support tab at the top and create a new ticket, with the reason/category being the delete option. Then, type in the game and go on. If you do this while a giveaway is still active, you will be successful immediately. If the giveaway has already ended, then the ticket will come to us to validate. You'll need the selected winner's permission to delete before we'll do that, and the winner is not obligated to provide that permission.

Sorry I can't be more directly helpful to the issue at hand, but do let me know if you need additional assistance (or you can always create a support ticket) and we'll try to help you out.

Thanks,

Gaffi

I own both so can check for you if you want, if so add me.