It's a bit of a rule that writers shouldn't give two characters similar names. The arguments go that it confuses the reader and should be avoided in the name of clarity. I usually subscribe to this view and I've changed a few names in drafts to improve the clarity and flow. However, in my latest novel, I've broken the rule - for what might be considered sensible reasons.
Back when I was working on the backstory for the characters of Max and Valerie, I named Max's parents, as you do. Sadie and Peter Jarvis didn't play a part in the first novel, although I had an inkling they would later on. Named and banked for later.
Stevie is a different matter. She was named in a (so far unpublished) novel that revolves around her. It was only after I'd written drafts about Stevie and her adventures that I realised I wanted to bring her into Valerie and Max's story too. I definitely wasn't prepared to change her name, but I still believed she could play a role in Max.
And that's why I've ended up with a Sadie and a Stevie in my novel. The two characters don't interact directly, so it doesn't get too complicated in that way and, trust me, they're very different people.
So, that's the story of why I'm breaking one of those writerly rules. I won't do it again. Unless, of course, I decide on another inconvenient crossover somewhere down the line.