Grumpy editor here.
This is one of my pet peeves, and I have it in common with other editors.
The first thing I do on any MS with this glitch is tell the writer to change the names.
I don't care if the characters never appear together in the same scene, are opposite genders, or have wholly different personalities.
I don't care if all the best beta-readers say different; they're not editors who have to deal with this all the time with a dozen other writers who really should know better.
It's not a deal killer, but it is sloppy writing.
Even if you did it on purpose and are not a sloppy writer, it
looks like you are.
Please don't send me sloppy writing.
It's more work for me. You don't want to give me more work. You want me to smile and ask for more of your wonderful words and to send you lots and lots of lovely checks!
It's an easy fix that makes me much less grumpy.
There are 25 other letters in the alphabet to use. Have some fun with them!
Tech trick: Divide a page into 26 squares and a single alphabet letter to each square.
As you name a character--the main name you will use throughout the story--put the name in its square. Then never use that letter again.
This is a very easy way to avoid the problem AND helps you keep track of the correct spelling of each!
One of my series characters has an oddly spelled name and this is the only way I can remember to get it right!