First time I'm ever hearing Pikmin 2's soundtrack being attributed to Totaka too. It's been a while since the last time I listened to the score in full but I don't recall ever thinking any of it was written by anyone besides Wakai.
There's an interview here with Totaka and Wakai that may or may not clarify things, if someone who isn't a scrub at Japanese wants to take a look at it:
http://www.nintendo.co.jp/nom/0405/1_2/