He he, I did not remember …
But not in the film. He may have had then his reasons to change that, maybe because he did not really want people to see Eastwood as the same guy.
And at least, as I said, in FAFDM he has a name, a typical SW name, and is is not Joe.
Of course one can interpret that in GBU it was big, bad war which fully transformed him to the character we know from the two previous films.
Only that he absolutely is already that character in the first minutes of GBU. He doesn’t change a bit, not in this one, not in the 2 before. Leone’s westerns are rarely about character development, they are not about “real” people (like Peckinpah’s).
And that is also the reason why it doesn’t bring the trilogy anything to view him as one character, it doesn’t add any depth to it.
The worst thing about the Eastwood character in Leone’s films is when he talks about buying a farm with the money in FAFDM. That’s a moment where I think Leone had at that point not really understood himself what he had achieved, or what he was going to achieve for the genre.