If they are as edgy as I suspect they are, they probably think having a double-flower name is neat. Or maybe they hardly see Rose/Violet as a flower name at all (I'm like that with
Iris - sometimes I forget its a flower)
It's not bad. Not something I'd probably do, but certainly not horrible. Celebrities do it (
Johnny Depp's
Lily Rose for example), so it seems ok to most people I'm sure.