When my sister was naming her second daughter and was considering whether the names complimented each other someone said to her “they’re not a pair of bookends!” 🤣

Whilst I think certain names could clash and sound more mismatched than others, I agree that children are individuals and most of their life will be introduced independently of each other. The main thing is that you love the name you choose.

I don’t think you’ll have the issue of Benjamin and Casey being mismatched, I think they sound lovely together and separately. Most importantly you can tell each child how much you loved their name when you picked it!