(Question contains spoilers)
In the film Welt am Draht (World on a Wire), somewhere in the first half of the film, Fritz Walfang enters the "one level down" simulated world, but instead of Fritz Walfang coming back "up", simulation unit one (named "Einstein") comes back in the body of Fritz Walfang, with their identities being swapped, and the real Fritz Walfang stays in Simulacron-1.
At the end of the film, Fred Stiller is shot and killed, but Eva Vollmer organises an identity swap such that he is able to come "one level up", to the "actual real world". Does anyone stay behind in the "main world" (in which most of the film is set) in his place?
According to Wikipedia, it was swapped with the "real Fred Stiller", but does that mean he was also in the simulation at the same time; two Fred Stillers in the same world?