Hello
What do you exactly mean for "Does StarGo2 apply to the M-Zero mount"? The StarGo2 Pro "Phisical" controller can manage the M-zero mount replacing the StarGo but the StarGo2 Firmware update cannot be installed on the StarGo "phisical" controller.
To clearify your doubt about the StarGo version currently installed on your setup, the 6.5.18 value refer to the StarGo.exe and match with the firmware v.6.5.6, so your configuration it is correct (see attachment).
You don't see the “Installer 6.5.18” since the Installer name version refer to the firmware and not to the exe.
Stefano
Avalon Instruments Team