sbm12, I find it surprising if JetBlue is actually rewarding the ticket buyer rather than the ticket flyer since I've seen very few promotions from any airline that do that. I think JetBlue was assuming ticket buyer==ticket flyer and did a very poorly worded promotion. Depending on how you interpret it, if I buy two RTs, one for my wife and myself, and we're both registered for the promotion, either I get 1 50 point bonus (for myself) 2 50 point bonuses (for both of us) or each of us get a 50 point bonus (for each).
Until they clarify (I'm going to email JetBlue to get their answer) I'd book each ticket individually under each person's separate CC so each person should get credit in the typical buyer==flyer scenario.