I don't know how you did the initial adjustment of the new cables but in general, you need to adjust the clevis pins on both motors. You probably only have to change one adjustment but which motor
The proper process is to disconnect the throttle cables on both motors, make sure that the throttle linkage hits the stop on both motors. Then make sure the control is in neutral and see if the connector on the cable end (motor side) slides onto the pin without the throttle moving. If it doesn't, you have to screw in or screw out the connector on the cable so that it does slip on.
Repeat for the other motor. If the throttle are still out of sync, look at the motor with the lower revs and screw in the connector a turn at a time and retry.
I think I made this sound more complicated than it is.
On other thing to check: with the throttle cables disconnected at the motors, start and run the motors till warm and check that they idle at the same revs.