Hi, using the GPX Plugin with Octoprint for my CTC Dual Extruder, these are my settings:
My octoprint installation is fairly old, I’m currently in the process of upgrading my current setup as I’ve acquired a Geeetech Prusa i3 X as well, but even this week I have successfully printed about 5 parts using the settings above.
I use ReplicatorG as my slicer software but I guess you could use others, as long as you end up with a proper gcode file in the end. As mentioned before in other threads, the CTC Dual Extruder is a Replicator 1 Dual clone, so you will need the GPX plugin up and running on Octoprint, in order for the gcode files to be properly fed to the printer.
Hope this helps!