First off I have never had an experience even remotely like the one described by Bluesky11.
Other than the standard reports of possession the only other reports that I have read about are about "walk-ins".
"Walk-ins' are spirits who inhabit another's physical body because either ---
a) the 'walk-in' is allowed by the other physical person's consciousness to enter or
b) the other person's consciousness (Astral/ethereal Body) has temporarily or permanently vacated their physical body.
The idea of 'walk-ins' does indeed seem very unusual. Yet what exactly is Normal where OBEs/astral projection is Concerned?

Anyway the point to be made here is that it is indeed theoretically possible for 2 consenting consciousnesses (Astral/ethereal bodies) to switch physical bodies with one another. Or to share a single physical body between them. (Perhaps that partially explains some cases of szchophrenia??)
Very unusual. Very rare. Yet it is at least theoretically possible.
Grey