I did a test with the Su-24T, since it's the only othre twin engine aircraft I own. I mapped my SINGLE throttle axis to both engines, then mapped increase and decrease left and right to q-a, w-s. I was able to push the axis up to which brought both engines up to say 75%, and then use the A button to bring the left engine back to 65%. Not what I want ideally but I can't afford a new throttle. The nice thing is that once I used the buttons to separate the output of the left from the right, they stayed at 10% different even when I pushed the axis up and down.
I have been thinking about this ever since I saw Kermit Weeks do a video of the cockpit in his Mossie and mentioned that for takeoff he used different power to the left and right engine to help control the torque on takeoff.