Title: Days/GREEN & GREEN/Days
Release: December 17th 2008
First press: Available for the CD+DVD-versions (appearantly comes with a picture label)
Type: Double A-side single in 4 versions
Tracklists
Days/GREEN (both CD and CD+DVD)
CD
01. Days -original mix-
02. GREEN -original mix-
03. Love ~destiny~ -10th anniversary version-
04. Days -instrumental-
05. GREEN -Instrumental-
06. Love ~destiny~ -instrumental-
DVD
01. Days -video-
02. GREEN -video-
03. Days -making-
GREEN/Days (both CD and CD+DVD)
CD
01. GREEN -original mix-
02. Days -original mix-
03. TO BE -10th anniversary version-
04. GREEN -Instrumental-
05. Days -instrumental-
06. TO BE -instrumental-
DVD
01. GREEN -video-
02. Days -video-
03. GREEN -making-
I don't know if these are counted as 2 singles, or as 1 single. 'Cos the titles ARE different, which is for the first time ever. Let's hope it's simply one single (which is most likely), for the sake of Ayu's #1-streak.
Oh Ayu...what's Greenday gonna say? 
source:
Ayu's official site