DUPLICATE STEAM KEY

As the title says, I tried to redeem my code for the current Flight happening this weekend, and next. Steam told me it was a duplicate key. This is the ONLY key I have left on my account, yes I’ve confirmed it’s the current one running these next two weekends. As I’ve not had a response on any of my bug reports, I take to the forums to gauge interest / see how many other people are having this issue? If anyone could also help / generate some new codes for us lowly’s who somehow got our’s used up. That’d be great. Thanks! Long live Halo!