Before posting my review of “The Good Mother” yesterday, I had to check IMDb to make sure I correctly spelled the first name of its lead actress, Hilary Swank. But when I searched using the movie’s title, I discovered there have already been at least two other movies with the same name.

One of them was a vehicle for Diane Keaton and Liam Neeson in 1988. Another was a TV movie starring Helen Slater in 2013. None of these had the same plot, nor were any of them remakes. There’s also been a movie called “A Good Mother,” the TV show “The Good Mothers,” and plenty of sitcoms that used the phrase in episode titles, too. Swank even starred in another movie called “I Am Mother” in 2019.

This is not uncommon. Earlier this year, Collider compiled a list of movies with the same name and found duplicates of “Night Moves,” “Twilight,” “Missing,” “Rush,” “Heat,” “Kicking and Screaming,” and several others.

This strikes me as odd because in the acting business, labor unions (e.g. SAG-AFTRA, Actor’s Equity) won’t allow you to register with a name already taken by someone else. Often, actors have to add an initial, such as F. Murray Abraham or Michael J. Fox. The rule is the reason a guy born Michael Douglas had to change his professional name to Michael Keaton so as not to be confused with the son of Kirk Douglas (who, incidentally, was originally Issur Danielovitch). If SAG-AFTRA had no such rule, that 1988 “The Good Mother” would have starred Liam Neeson and Diane Hall, her birth name.

Show business is not alone in imposing the first-come-first-served edict regarding names. In horse racing, no professional thoroughbreds are allowed to have the same moniker — or even one that sounds similar to another. This probably has to do with ensuring there’s no confusion among bettors: “I said $100 to win on Pain In The Brass, not that nag Pain In The Grass!”

That’s why you’ll never hear of another horse called Secretariat or Seabiscuit. Unless they star in a new movie called “The Good Mother” — opposite Swilary Hank.