I've had the experience of actually laying back down into my body to wake up is it possible for two people who can leave thier body to simply trade? Is there any groups or research being done to test any of this stuff in the field?
Technically, when you 'leave your body' it is your awareness that leaves, not the entire you, which accounts for the bilocation experienced by many. So I'm not sure how you would achieve this except by 'merging' both consciousnesses. But the idea is intriguing.
Projections are just energy dubbles being made by you, you put your mind into them. If you were to try that with someone and switch. At best you would recive each others energy and the mind would return to its proper body, since it doesn't really leave, just switches focus.