Psychic A, in his home at the Capitol on Golarion, casts create mindscape and then makes it permanent. They then tell a friend, Psychic B, who is currently in the Elemental Plane of Air.
Psychic A & B both cast mindscape door to enter this already established mindscape. There are now two doors, one to a house in Golarion, another to a place in the Plane of Air.
What happens if Psychic B then walks over and goes through the mindscape door to Golarion, and A goes through the other to the Plane of Air?
When you exit through either door your mind returns to its body.