I too have the Toauto A1,.. attempted dual extruder with robin nano, plus toauto's firmware (created on the spot !!!,.. even though they advertised dual color when purchased) I have seen no indication of second extruder in menu since flashing said firmware,.. pretty new menus though !

Do I need to change jumpers to use parrallell splitter ? neither z motor responds at present.

Are you aware of dual extruder firmware for either the robin nano, or the skr you mentioned ? I have the skr 1.4 turbo as well, in surplus.

In all actuality,.. I have 7 printers, 4 down for repaires/upgrades atm. In attempting such repairs and upgrades, I've found that the makers of one of those printers, alphawise, is out of business. np. I'll make them ALL into one model. One that has power out resume plus filament run-out detection,.. I figured cr 10s. bad choice as their boards are the most expensive for what little they can do !!!!! I also want multi-color,.. how about 9 color ERCF mmu,.. but now, are the voron machines, they ONLY work with, a total different monkey than the standard gantry style printers ? I only have those type printers. I imagine I may have to reverse some motor directions in klipper, which I know nothing of.