@Caine-One1 Hi, I'll move this to the DE Origin section, perhaps someone can better explain this in DE there, as this is the EN section for discussion of the website.
Anyway, for your issue, you don't need a 2nd key at all. On your 2nd machine, download the Origin client and log in with your existing account, and you can download and play FM14 without needing to take any further steps. This is assuming that you are referring to FIFA Manager 14 of course.
If you mean Sports Interactive's Football Manager 14, this isn't our game, and we don't sell or distribute it. However, it's worth pointing out that if you use steam or another distribution service, you can likely download the client on your 2nd machine and log in there to download it too.