MT2 responds only to MIDI messages and those which are... note on/off and velocity. It means that to pad knocking that MT2 will respond, but these knob turning messages are ignored since the CC messages MT2 does not support for _recording_, however it sends out them if you enter manually in track.
I have enough controllers and midi devices, and all those which send pitch bend, program change or CC (knobs!) are ignored by MT2 while recording.
Just one thing more. It can be complicated to add together with Your existing midi keyboard, becouse both these keyboard and pad controller must be mapped to the same port. How You add these together -- with software or hardware -- is up to You.