Answer: Good to hear from you, Donna. There are several things an author can do to avoid confusion among characters.
First be certain that the names and descriptions are all different and work with the personalities of the individuals. Each of the three should want something different. They should be different physically, too. They may be of an age, but make one a blonde, one a brunette, and one a redhead.
Be sure the names don't start with the same letter, so the eye won't be inadvertently confused as well. Readers, especially those who "skim," may often confuse characters whose names start with the same letter. They might even confuse Roger and Rhonda if they read quickly enough.
Then if a character turns up after an absence of some time, especially minor characters that the reader may not remember, then give an explanation of who they are when first mentioned anew, to cue the reader as to their place in the story. Here follows an example:
I was pleased to hear from Donna, an old student of mine, that three of the stories we worked on together had sold.
If this were part of a story, and"Donna" had been missing from the story's action for several pages, the cue -- an old student-- will place the character in the mind of the reader. These little cues and reminders go unnoticed if done right. They don't get in the way when the reader remembers. And they take up little space and keep away confusion if the reader has forgotten. Remember confusion is the first deadly sin of writing.
If you can get hold of a copy, you might want to read Dick Francis’s THE EDGE, and study his reader cues. It’s a mystery set on a train trip across Canada. He had several sets of characters: the detective and security people; the horse racing crowd — villain, suspects, owners, and horses, etc.; the train crew conductor, kitchen staff, etc.; and finally, the cast of a mystery play who were performing to entertain the party. He managed to cue the reader every time, with (I counted) upwards of 40 characters involved, that was not an easy task. But he is a masterful writer.
I hate it when critics say, “Francis is an excellent writer for a mystery writer.” As if mystery writers don’t have to be very good — or as if it’s a surprise that a mystery writer should be “excellent”. Francis is excellent, his images flawless, his attention to detail phenomenal, and his reader cues infallible.