DKP and DKJ were famous for switching between octaves during a song. For example, they would sing a line in one octave, then switch to the higher/lower one. I suspect this was because they used to sing together, hence had to choose a sruti that was somewhere in between their own 'natural' srutis.
I think Brinda/Mukta also used to do this? Any other singers who are known to have sung in this way?
And is there a technical term to describe this 'style' of singing?