Yeah, I noticed now because they spoke within 30 seconds of each other. I never paid attention to voices much in the KH2 days, other than the Billy Zane-->Epcar transition(Epcar did very well this time too).
And yes I agree, the voices are pretty accurate to the characters' personalities.
Ah, I see, well, I did pay attention to several voices later on, also since we had KH1 and KH2 with German voices so I needed to get familiar with the English ones anyways.
Richard Epcar is really improving more with each appearance since CoM where they made the mistake ordering him to try and match Zane from 1. If he can do the voice freely he's much better and that shows, also because he's dedicated to his role in the Series just like Quinton Flynn, David Callagher, HJO and Jesse McCartney are.
The few voiced scenes in Days also show pretty good the more melancholic, reserved voice of Roxas, while Ventus is more outgoing, a tad louder and definitely brighter and higher-pitched in general.
I've always loved Jesse's performances, I feel that he's been consistent with both of his characters more than anyone one else in this franchise!
Even after HJO's voice changed, I felt that he got better with each installment too. I know people keep complaining about his voice, but I love it! The man truly knows his characters and he's excellent in every performance!
Dito, I also give him much credit for his management of the voices of both characters.
The main problem may not even be HJO's voice in itself, but the by now annoying habit of using the younger Sora-model. I sincerely hope that DDD was the real final time we have to put up with KH1-Sora and the next title(s) stick with Sora's older model, not forcing HJO to try make his voice sound higher-pitched to match the younger Sora.
Vanitas is in that regard easier to voice since he a) has the older body constantly and b) his voice is generally deeper than Sora's (I would even dare say that out of the quartet Sora/Roxas/Ventus/Vanitas he has the deepest voice).