Not quite the same situation but I know a family where the young man found his birth family (after he had left for college). And he found his birth parents had stayed together and he had quite a few full blood siblings and one of them shares the same name. He’s established a good bond with them all and the sharing a name doesn’t bother him (or them) one bit. But of course they didn’t grow up together.
I also know a family where they intentionally named all their children variants of the same name (think [name_m]James[/name_m], [name_m]Jimmy[/name_m] & [name_m]Jim[/name_m] or [name_m]Andrew[/name_m] & Andrea) and while it can be confusing and they never did nicknames, they figured it out and none of them are worse for the wear. Though it did cause minor annoyance when others tried to use nicknames and they had to clarify.
And last one, I know a blended family where they had two teenage girls the same age, and pretty much the same just slightly different pronunciation (along the lines of [name_f]Hannah[/name_f] vs Hahna) and the girls get along great, and at least outwardly it doesnt seem to bother them much.