Back 20+ years ago, my uncle used to be an artist at Disney, in their department that made the movie posters. The way they ran it back then, three of their artists were assigned to make a poster for a movie. They were each pretty much given free rein. Then the execs would pick the one they liked best out of the three. I have no idea if they still work the same way today.

Visiting the office was kinda spooky. The walls were covered with posters that weren't selected, of famous movies. It was wierd seeing a unrecognizable posters for movies that you were familiar with. Spooky, and kind of disappointing because some of them were really good. I especially remember my uncle's poster design for "One of our Dinosaurs is Missing" - it was WAY better than the one that was selected.