My recording of "At Midnight" on Comedy Central, which, as you'd guess, airs at midnight (I think it may technically start at 12:01), ended up being an HOURish long recording last night, with The Colbert Report AND At Midnight. (ish because I pad most recordings, esp Comedy Central, on both ends.)
Strangely, my Colbert Report recording ALSO recorded.
My 11pm recording of Arsenio didn't record, since it thought there weren't enough tuners (no big deal, since I just FF through it 99% of the time and delete it).
So I think I hit some other weird edge case of the padding and/or use-same-tuner bug.