Ania
Sometimes they're told to change their names because someone else has/had it before. Case in point:
Michael Keaton. He was born
Michael Douglas , but, as you know, another actor had that name in Hollywood before him. And he couldn't use
Mike Douglas because of a singer whose name was originally
Michael Dodd, but was told to change it to
Mike Douglas by the petaybes.
Another case in point: After the shooting death of
John Lennon, this one actor (I can't remember his name off-hand) had trouble getting a job. Why? He originally had the same name as the person who shot Lennon (either that or his stage name was the same. I forget which).
Besides, some of them use stage names to protect themselves from stalkers and other major irritants (
David Letterman springs to mind). It's much more difficult to find someone if the "public" name and the "private" name is different.
Phyllis