Just crossed my mind.
Say you and a friend both did a FAA PPL. For hour building you both chipped in to hire a very basic and relatively old twin. According to FAA rules then, you both could log P1. All you got to do then is convert to a JAA PPL and carry on your commercial training from there.
Advantage gained: Multi time built at minimal cost to each party. Sound like I found one? (a loophole that is

)