That’s what I had in mind
Two separates controllers coordinated by a single klipper board
I think they’re seen as a single “printer” afterward
It’s initually meant to keep the cost down when you need a lot of axis, as you can but multiple cheaper controllers (an skr pico with 4 tmc2209 costs 20-25$, you can get 8 outputs for less than 50$)
They would be annoying if I didn’t also have the manual switch wired in parallel so simple jobs can run manually and don’t have to mess with the spindle on/off in the gcode.