At the time George Lucas was holding auditions for his film, director Brian DePalma was also holding auditions for the horror film “Carrie”. A few actors who auditioned for one film, may have gotten a role in the other. There was a rumor, later disproved by actress Carrie Fisher, that Sissy Spacek was originally cast as Princess Leia, and Carrie Fisher as Carrie.
A notable example is actor William Katt, who auditioned for the role of Luke Skywalker with Kurt Russell as Han Solo. Katt later got a role in “Carrie” as Tommy.