Apparently that happens with real people, or at least their estates, as well.
In Elton John's movie "Rocketman," he is asked to come up with a new name. Per the movie, he got Elton from his band's sax player Elton Dean, and his last name from John Lennon. This is a blatant error, even more amazing because Sir Elton was the Executive Producer of the film.
"John" came from blues singer Long John Baldry, who was the leader/vocalist in Bluesology, the band he was with at the time, and who convinced him to come out of the closet. In fact, the song "Someone Saved My Life Tonight" is about Baldry convincing John to come out. Why Baldry was never mentioned in the movie, I have no idea. Maybe his estate wanted some extra money for it (he died in 2005) or they had a falling out over the years.