The two tracks that Yasui & Saso are co-credited for both contain two pieces of music, so my guess is one composed one part and the other composed the other part. They're credited in SuperSweep's blog entry as "Yousuke Yasui ~ Ayako Saso" both times, so I'd think that Yasui composed the first parts (Net on Fire and Navi Battle) and Saso composed the second parts (Eyecatch and Clear).
I could just be pulling that out of my butt, of course.
