I heard a father calling his twins the other day: Chloe and Zoe. Both nice names on their own, but how confusing! A mom in my homeschool co-op has Naomi and Fiona, and I like that pairing a lot better. They have a similar sound (three syllables, emphasis on the second, consonant-vowel-o-consonant-vowel), but aren't matchy-matchy or rhyming.
I forget if I've told this already, but when I gave birth to my youngest, who is actually Lavinia, my nurse commented that her name was just like the other baby born that night, whose name I forget but was something like Paxton. She'd never heard of either and thought they were both made up, and I was surprised to realize that Lavinia wasn't as known a name as I thought it would be.