Well, in retrospect I might've been exaggerating there with the word "some", seeing as the only noteworthy character I can recall that was in all three games and had a different voice in each was Helmer.
But still, the vast majority of the cast had two different voices throughout the series. The only characters that were in all three episodes and had the same voice in each were the URTVs, Ziggy, Allen and Margulis. Everyone else changed at least once. Hell, the two most important characters, Shion and KOS-MOS, got different VAs for Episode II, only to change back to their original ones for Episode III. >_>
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Time waits for no one.
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