Of course, you can do that. Basically, you need to set up your presets beforehand. Say you have two preset lists on your two H9s:
First H9: 1.Pitch 2.Dirt 3…4…5…99
Second H9: 1.Dirt 2.Pitch 3…4…5…99
Then you can connect your MIDI controller to the first H9, and connect your first H9's MIDI OUT to your second H9's MIDI IN. Then you should be able to switch to any pair of presets together by sending one MIDI PC message from your MIDI controller.