I've discussed this elsewhere here on the Q&A, but if you have two Presets supercontrols -- whether they are also Channel Changers or not -- they will overwrite each others presets. The way to avoid this -- and this solution is only valid for non-channel changers, clearly -- is to use different MIDI ranges for the supercontrol... this is because you get one value per CHANNEL (MIDI value) for the supercontrol for each subcontrol. Sorry that's a bit complicated. Mi spiego ;)?