This is pretty good, isn’t it? The story goes that the name Revenge of the Jedi was used for the movie Return of the Jedi used by the Lucasfilm company to try and fool the media and press but movie studio Twentieth-Century Fox picked up the name to promote the movie, well before Goege Lucas gave them the permission.
Another story is that George Lucas thought that the movie name Return of the Jedi wasn’t a strong name and later thought to name it Revenge of the Jedi but others believed Jedi's don’t go for revenge so the title would be wrong.
And another story was Howard Kazanjian made up the title Revenge of the Jedi to try and stop the huge amount of black market items that would come out before a movie is released. There are a few items that have the name Revenge of the Jedi instead of Return of the Jedi, especially Star Wars figures and they have become very rare and very valuable to collectors.
click picture for bigger version.