Question about un-numbered demos [[singles)

[thomas96]

Does anyone know how many un-numbered demos were made and for which songs that went un-released as singles? Also, does anyone know why they were made as demos and went unreleased as singles, instead of just being made on acetates?
For examples:

http://www.popsike.com/php/detaildatar.php?itemnr=300563708052

http://www.popsike.com/php/detaildatar.php?itemnr=250320087641