I don’t think they sound all that similar. They do end in the same sound, but if you’re okay with having two kids whose names end in “lee” (maybe as a cute connection between the two of them), it could definitely work. I feel like [name_m]Ry[/name_m] and RyRy are such natural nicknames for [name_u]Rylee[/name_u] that it weighs out the possible too-similar concern. Because as soon as you start calling them [name_m]Ry[/name_m] and [name_u]Bradley[/name_u] (or a nickname for Bradley), the names immediately stop being similar at all.