I heard about the story about how Paramount turned down the Babylon 5 pitch, then turned around and made Deep Space 9. Of course the two shows went in different directions, and are each great in different ways. But there are eyebrow-raising surface similarities. Both shows are named after a numbered space station, feature a commander who is a prophesized savior, have long story arcs, explore moral complexity.
Yesterday I watched the movie pilot, The Gathering. There is another similarity I hadn't realized before: both commanders are romantically involved with a freighter caption whose name starts with "Ca"!