This is right and i totally agree with you.

But I only want that we ll able to do a custom battle romani vs romani.

This way is possible if we make roman units playable with other factions (also rebels if you want).
The discussion about campaign was close many weeks ago.
I talking only about custom battle.
Because in EB 1 we can play barbarians vs barbarians, hellenic vs hellenic, nomads vs nomads, but we can t play romans vs romans.
This is only thing that I would see in EB 2... nothing else.