DVR Changes Channel to Record Without Warning

The Comcast DVR gives no warning before changing channels to record. When the DVR wants to use the second tuner to record, it just changes the channel. This means that if I am watching a live show on delay when the tuner changes, I lose the recorded portion of the show I was watching, and returning to the channel does no good because I was watching on delay. I have missed the end of numerous movies like this. TIVO warns and gives the option to cancel the recording. Comcast should do the same. There is no excuse for this to be a problem with Comcast.

And, to make matters more frustrating, the DVR is often doing this to record a second airing of a show that was recorded earlier that day, even though I have programmed it not to record repeats.