Well, I didn't intend for it, but I have a few characters with similar names, or rather when you shorten their names, they're similar.
Charlotte - Char
Sheryl - Sher
They're related though, so it works out.
Also, Charlotte has a niece names Shana, which also has a similar sounding name to Char and Sher.
Basically, I think as long as people can tell who is Cassandra and who is Sandra and who is Dan and who is Danny, it shouldn't be a big deal.
Now if they were twins both named Daniel...first I'd have to say the parents were super unimaginative for names... XP
I've recently felt this way a bit myself as I saw some commentary on the "blog we do not speak of around here" about my comic where there were comments ripping on my art a bit as well as my comic in general that has made me a bit more self-conscious.
However, I am trying to use those trolling comments to better myself, use it more as a harsh criticism and learn from it somehow to improve.
I can't let the trolls win. I haven't done my comic since 2014 to suddenly allow some anonymous trolls to break me now. I've had too many points in my life where I attempted to do a webcomic, but chickened out for various reasons like my writing sucked, or my art wasn't up to snuff to do some things.
I say to all those insecure about your work to quote a certain actor's infamous video... "JUST DO IT!!!" Do what you want to do with your comic. Ask for critiques on your art, your dialogue, etc. If you firmly believe in your comic even if no one else does, then keep at it. Your art, your writing...everything will improve in time. Use tutorials, talk with other artists/writers. Heck, if you have money, maybe even take some classes at a community college just for the experience. Whatever it takes.
I know we all have busy lives probably and maybe your comic is a hobby, something you do on the side, and if so, it's understandable to feel burnt out a lot, but never give up if you have a story you want to tell, a scene you want to draw...
And if all else fails, take breaks. Time away can make you feel better, make the creative juices pump again. If over time, you feel the comic isn't working out like you wanted anymore, you can always reboot, but I generally prefer to mention this as a last resort as it were.
Just don't give up if you really still want to do something with your comic.
I asked in a similar created thread about one of my main characters that has 'dot eyes' if I should change them, and from what I recall, most said they felt I should keep them as they were a part of his character.
The funny thing was I started drawing him with those kind of eyes initially as a nod to some comics I used to read years ago.