Kinda defeats the purpose of Biggs going of and joining the ACADEMY run by the empire, guess he bailed out at the last moment cause of all the clones...
Or the fact that Luke also wanted to join even though he hated the Empire. (hmm kinda like what a lot of people that join the military today do, they don't do just cause the like the goverment in power.)
Personally I think that is a strong arguement that they ARE NOT all clones. Also why the reason Clonetrooper was dropped for Stormtrooper, cause eventually they weren't all clones.
Course, Boba Fett would probally feel pretty unnerved walking around with all these guys that look and talk like him. Which btw would be a good reason to keep his voice unchanged... his helmet actually changes his voice, so its different... much like Leia's, Boushh disguise.