My brother and me made custom speech, we have 2, when we play in a LAN game, only one of both speechs are the custom, the other one is just the standard. why?

I am pretty sure when playing lan/net games, only you can hear your custom speach. Your opponent will just hear the standard speech bank.

We have 2 foldiers of custom speech in each computer, with the same names: [Jorge] and [Antonio], but when we play, the speech [Antonio] changes to speech Spanish-2

I am pretty sure when playing lan/net games, only you can hear your custom speach. Your opponent will just hear the standard speech bank.
That is correct; unless your opponent has the same speech bank saved under the same name (or if they have a different speech bank under the same name, they will hear that).

Isn't there a bug where only one team can have a custom or stock speechbank and all others switch to the default language of the installation?

I fixed it! =D
We have both speech foldiers on our computers.
I just put my sound bank into the "Hispanian" speech foldier, my brother's speech is corret, and mine changes to the Standar one (Hispanian), then it sounds like I want ^^