Both volume 1 and 2 were released separately on iTunes:
https://music.apple.com/jp/album/unr...l-1/1482827186
https://music.apple.com/jp/album/unr...l-2/1482823554
"audition edit" was nothing but a sample track. It was added because Nakano disabled the ability for people to listen to each track fully without purchasing. Quite a few artists do this on Bandcamp.
Also: Dewprism 20th anniversary interview (In Japanese):
https://www.penguinslabo.net/gmusic/dewprism20th/