If you are recording on program on one channel and watching another channel, is the box recoding twice?

E.g. the program you are recording and the live buffer of the channel you are watching?

And is it 3 times if you are recording 2 channels and watching another?

The reason why I ask is that I keep getting a reboot when I change channels too often while recording.

In the chaos after the election coverage.. i kept on getting such re-boots with switching to Radio..

If recording one and watching another then yes the one you are watching is being recorded to the time shift buffer.

Under some circumstances you can actually record three.

If the two recordings are from the same transponder for example 108 BBC-HD and 951 BBC 1 CI then only 1 tuner is used so you can view any other chanel and it will also be buffered. (You can pause it live)

The other way that you can watch a 3rd channel is that you can watch any channel sharing a transponder as either recording. In this case the 3rd channel is not buffered (No live pause)