Surely the marketing or developer relations team has a better handle on this...but I vaguely remember hearing that DevCon perks were not necessarily directly linked to email address ( when you registered ).
It was about 6 months or more that I heard that...so I'm not sure if that's absolute truth or not.
Thanks for checking in about this. I'm pretty sure that each FM Community profile can only be associated with one email address. However, DevCon perks are not associated with FM Community accounts this year, so you're not missing out on anything from that point of view.