When you link the controller to the drone do you, in the App, see the option to specify whether the controller is the "primary" or "secondary" or perhaps master/slave?
With the
M2P/Z, both of which allow two controllers the App ( Go4, same as the
MA ) offers this option.
With the P3Adv and
Mini 1 & 2 their app DOES NOT offer the option and effectively links a 'new' controller as the primary, displacing the old controller..
If you do not see the option in the App then I doubt that it is possible to have two controllers linked to the
MA.