My Guide Data shows this:
Heroes NBC 9-10:01
Journeyman NBC 10:00-11:00
Obviously, this guide data is wrong. Since the shows are on the same channel, there cannot be a 1 minute overlap. The ?bug? is that TiVo doesn't notice they're on the same channel; on a single-tuner box it clips (if clipping is enabled) or won't record one of the shows, on a dual-tuner box it records them on separate tuners. If I try to record today's 1-game playoff between the Padres and Rockies, TiVo will cancel whichever of these two shows has lower priority.
The wonderful end to this story is that TiVo says "we get our guide data from Bright House, call them". Bright House says "we don't support TiVo, it's not our problem".