I was in mother's group with a J family like that - mum and dad both had names starting with J and named their 2 girls names starting with J. Personally I couldn't do it as it is confusing with having mail addressed to you etc. but having said that I have a G & J name that have the same starting sound so I am a bit of a hypocrite
They aren't the same at all!!!! My friend has "Olivia" and "Bianca" which she now thinks are too much the same but at the time she didn't notice it...

Personally I'm not a fan. This may be off topic but my sister has a bigger problem with all the letters in her kids names being 'above the line'. So no f, g, j, q or y!
Yeah ok that's a bit odd... besides when you write a name you use a capital, don't you? So they are all automatically above the line?

I thank you in anticipation of your consideration of my consternation...

I am not a fan (unless you are in a Gilbert and Sullivan opera).
I am the very model of a modern major general!