This one's damn good, prepare yourself.
I dreamt that there were doppelgängers.
In space.
As you probably know, doppelgängers are entities that mimic/take the form of another - indistinguishably, almost. However, they can't be killed by mortal means, so they don't need to breathe, eat, or sleep. By this logic, they can go into space without any adverse consequences, and so they went there.
In the dream, I was an astronaut, and I was riding on Apollo >17, going to the moon with my girlfriend. Trip went by, and when we got to the moon, we were completely surrounded in doppelgängers of ourselves. It was loving horrifying. And we all died! It was really quite tragic, actually.