For some reason if you download all three files as one zipped file through the interface one of the extruder files is corrupt. Simply download them individually on the thing tab and it works just fine.
Just checked and this still works with the new Cura 4.0!
I created another machine profile, but this time it is for the Geeetech A10M. This profile works with Cura 3.5 and above if you follow the directions, and it may also work for previous versions as well. It just depends on when Cura started supporting dual extruders! There may be more tweaking needed for those who have custom GCode settings in the start and end gcode or nozzle areas. After adding this printer profile to Cura, you can simply click under the "Other" when adding a printer and there you will find "Geeetech A10M" listed. Here are some basic instructions to make this profile work for you:
(EDIT: Change the "x" in Cura 2.x or 3.x or 4.x to with whichever version you have. So if you have 2.6, replace the version number with a 6, or 3.0 replace the 2.x with 3.0 and so on and so forth.)
For a PC-
Put the "geeetech_a10m.def.json" profile file in the following directory (where the x in 3.x represents the release number):
C:\Program Files\Ultimaker Cura 3.x\definitions
C:\Program Files\Ultimaker Cura 4.x\definitions
Next, put the "geeetech_a10m_extruder_0.def.json" and "geeetech_a10m_extruder_1.def.json" profiles in the following directory (where the x in 3.x represents the release number):
C:\Program Files\Ultimaker Cura 3.x\extruders
C:\Program Files\Ultimaker Cura 4.x\extruders
For a Mac -
Installing this profile on macOS:
Open a new Finder window.
Type Shift-Command-G to get the "Go to location" prompt.
Type: /Users/your_username/Library/Application Support/cura/3.x/definitions
Copy the profile.json file into the definitions folder.
Type: /Users/your_username/Library/Application Support/cura/3.x/extruders
Copy the extruder.json files into the extruders folder.
Quit and restart Cura - it only reads new definitions while starting up.
Now launch Cura and add your new printer using the new profile! Good luck!! You are welcome to edit the start and end gcode for the printer as well as to make any other settings changes you see fit when you go back into the machine settings. I have just given you a starting place for now! Also, any newer minor releases of Cura (like 3.4 to 3.5, or 3.5 to 3.6, and now 4.0) will require you to place these files in the new directories. If it is just a simple update (for example: updating Cura from 3.5.1 to 3.5.2) then you should not have to copy the files again.