Legal Question in Civil Litigation in California

It's not clear exactly what your brother did, but my sense is that he had his first name legally changed to be the same as yours. I don't see anything unlawful about that. It's weird, but it seems perfectly legal.

Nobody "owns" their name. I'm certainly not the only Edward Hoffman in the world; last time I checked, there were three others practicing law in California. We all have separate identities even though we share the same name. If somebody else wants to have his name legally changed to Edward Hoffman, he would not be violating any of my rights. That would be just as true of a sibling as it would of a stranger.

If your brother tries to use his new name to make people believe he is you, then he might be guilty of identity theft. But merely having the same name as you would not be a problem. The crime would be using your identity, not adopting your name.

So everybody in the world named Larry has stolen your name and can be sued for that?? Your brother, like anyone else, can call himself whatever he wants, as long as he isn't doing so for credit fraud or identity fraud.