I'm always a bit baffled by these threads -- are there actual adults out there in the world whose immediate response to someone telling them they're thinking of calling their baby something entirely ordinary like Lana, Benedict, Flora or Audrey is to wittily reply: 'Lana is 'anal' spelt backwards!' 'Benedict sounds like 'bendy dick', Flora will 'spread easily' and 'Audrey sounds like 'orgy''????
I mean, are those honestly the associations their minds automatically make (in which case these conversations say a lot more about them than the names in question), or are they consciously trying to think like dimwit playground bullies, and genuinely believe they are protecting poor little Baby Lydia from being nicknamed 'Chlamydia' in fifteen years time...?
I would say, though, OP, that, given you already have a Grayson, that having a Clayton as well does sound quite similar -- same two vowel sounds in the same order, same emphasis, similar-sounding initial consonant...?
Our neighbours have a Jude and a Luke, and the mother is always complaining that neither comes when called, as only the 'oo' sound travels at a distance, and each assumes its the other who is wanted.