The first time I set up mythtv with my haupauge pvr150, all the channels scanned correctly and the listings from schedules direct corresponded accordingly. Now, I think because mythfilldatabase ran automatically over night, the channel listings don't match up. Example: channel 6 should be ABC. schedules direct however is showing the listings for channel 2 instead. So, mythtv records the wrong channel, but labels it as the correct show.
With my PVR-150 I didn't use the "scan for channels" button at all. I simply attached my schedules direct account to it and let it find the channels from there.
If I was you, I'd go back and delete the sources and recreate them. Maybe even go so far as to delete the sources, inputs and tuner cards, in that order.
I can't remember the screen, but I think you can have it find the channels from the schedule direct file. Use that one, instead of scanning the tuner card.