That poses an interesting dilema. Can one pax get BPs for two seats on the same flight?
Sure, just not under the same name. Many airlines will sell you a seat for Lastname/EXTRASEAT and let you have two next to each other. Most don't allow accrual of miles on the second seat, and certainly not to be credited to your primary account. CO is entertaining the idea of allowing the second seat to accumulate miles, but they haven't done it yet.