The only TRUE b-sides we have for MTM are Across The Line, What We Don't Know and Blackbirds. They were finished and the only ones to have the ''Unreleased 2007'' tag on them + Blackbirds was confirmed to be from MTM and they even showed a clip of it on the Making Of MTM that sounded the same as the version we got. All the other demos we got from MTM on LPU CDs and stuff are just demos that never were completed from the MTM writing period.
As far as stuff like Pretend To Be and Not Alone go, they were originally demos from the MTM era that the band later reworked and used them for their releases. The band does that a lot. Debris is also one of those songs, it was written during the MTM era according to LPU12, but we knew it was on the Meeting of A Thousand Suns DVD, so they obviously worked on it during that time as well.
We may never get the ''17th song'' for the original 17 songs that made the cut. We have 16 as of right now... Maybe it was a song that was later reworked or appeared on ATS or LT? I also think there was this demo constantly on the demo boards back in 2006/2007 that was called ''Ammosick'' or ''Amnesick'' something like that, maybe that was it, and we just never got the demo. I wish there was a way to ask Mike about the whole 17 MTM original track list or whatever. We basically have it solved except for 1 song!!!