as I understand and was taught, the ONLY way to identify a problem engine in a turbo prop is by "TORQUE, TEMP, and FUEL FLOW". In the case of an overspeed governor failure, sometimes you might need to take your feet off the rudder pedals (but not too far) and see where the ball goes. Sometimes a bit hard to read a couple of percent on the on the gauge.
To repeat earlier, dead foot - dead engine in a turbo prop can very quickly lead to a dead pilot.
