my list with singles/album is organized with the way that digital and mini-albums is "numbered" with "a", for example my list with album looks like this:
1. A Song For xx
2. LOVEppears
3. Duty
4. I am...
5. RAINBOW
5a. Memorial address
6. MY STORY
7. (miss)understood
8. Secret
9. GUILTY
10. Next Level
11. Rock'n'Roll Circus
12. Love songs
12a. FIVE
13. Party Queen
That's why they have "their" numbers xD I also do this with "digitaled" singles.