This level shows that rooms and portals are in fact static. So, the room numbers are never changed and portals always lead to the same room. Only contents could be swapped.

Lara starts in room 2 and portal leads to room 0. But the portal from room 0 leads to room 1 instead. So, when Lara stands before the doorway you can see different rooms behind her depending on the camera direction. When she leaves that room she can't get back and is only able to travel to room 1.
