If used with a dual-head printer, Palette™ will currently use the primary nozzle, then leave the other nozzle unused. So, Palette is compatible with dual extruder printers right now, but it only uses one of the heads.
We plan on adding support to allow the second head to print with another filament in the future. We expect that we will work on and release this feature in the next few months. It's all about how our software handles the Tool Changes in slicing!