I kind of think that regular clones don't. I'm not sure about commandos though. They may have just did that in RC to diversify the clones. Of course, a game can be a source, so maybe they do have different voices.
(^Click the pic to reveal my...) | Republic Commando: -]RC[-AjaX
BF2142: -]RC[-Auxidus | www.redcellgaming.com (I really need a userbar, eh. >.<)