I am just asking to try and understand what you are doing.
Are you starting and running up the engines in this order?
- Select Engine 1
- Start Engine 1 - make sure it is running
- Select Engine 2
- Start Engine 2 - make sure it is running
- Use the "Select All Engines" Command
- Apply the throttle and both engines RPM should climb at the same rate.
You could start engine 2 first I just used engine 1 for my example.
If you have the "Select all Engines" command set with a joystick button then try another one or add a keyboard command and see if that fixes the problem.
Wheels