I was under the impression that an actor/actress's screen name was protected, to the point that one couldn't even use the last name of another star, but I guess I was wrong, because a movie that I'm watching: Federal Fugitives : Producers Releasing Corporation : Free Download & Streaming : Internet Archive
Has an actress named Doris Day in a leading role (Rita Bennett), which is part of the reason that I chose to see it.
However, after realizing that this Doris has no resemblance to the better known one, I checked and found that the one in this movie had a fairly short career (1939-1943), playing mostly uncredited parts. The better known Doris's filmography goes from 1948-1968. As far as I have found, there is no relationship between them.
Are screen names protected or not?