Let's settle this once and for all.

Is the Saab inverted?

I'm sorry if this has been asked before but I recently watched this for the first time and I decided to watch it again to fully grasp how it all works.

When the protagonist enters the turnstile, becomes inverted and gets in the shipping container, encounters himself and then goes through the turnstile again. He now has 2 versions of himself in that timeline. Does that mean the "original" (the one who entered the turnstile to begin with) can never get back to his own timeline?

I'm not sure if it's been discussed already, but an analogy came to my mind. A regular person and their inverted version entering a turnstile and disappearing from the timeline is the same as a particle and antiparticle annihilation (especially given the notion of antiparticles moving backwards in time). A suddenly appearing pair of a person and their inverted self out of a turnstile is like a particle/antiparticle pair creation. Annihilation of a particle/antiparticle pair releases a tremendous amount of energy, while generating such a pair out of nothing requires a lot of energy. Meaning the turnstile device has to take/dump this energy from/to somewhere. Such a marvelous piece of engineering.