Well look what popped up on Ebay.
I don't know how legit they are. I've never seen season 2 or 3 promos out there before and all the bogus copies of season 1 I've seen don't have this artwork.
Season 1 here seems to have less tracks than the "leaked" mp3 set and so are possibly not from the 'stolen from Mark's studio' occasion.
I see the sets use the catalogue numbers MSCD 01, MSCD 02, MSCD 03. The digital Best of Millennium release used MSCD 04 which makes sense. Perhaps these promos were intended for commercial release at some point and instead a Best of the 3 seasons only was favoured picking tracks from the promos.