Have you ever been reading a novel and got confused as to which character was which? It’s happened to me several times. One of the main reasons, I found, was that if two characters names began with the same initial letter I get confused. I’m sure not everyone suffers from this disability but I do. I also get confused if two characters have only one syllable to their name even if their initial letters are different. Sad, I know.
Anyway, just in case any of my readers suffer from the same handicap I took to trying to make my characters’ names a different as possible. So I would just work my way through the alphabet using a different initial letter for each character. I also tried to vary the number of syllables. Another thing I found helpful was using foreign names.
Of course that doesn’t stop readers from forgetting who your characters are for different reasons – for example if they are too similar in other ways; or too boring. But then, if they’re too boring you may as well save yourself the trouble of writing anything down anyway, no matter what you call your characters.