Most multi engine instructors require their students to not only identify which is engine has failed following a simulated engine failure, but to confirm by pulling back the throttle of the "failed" engine despite that throttle has already been pulled back to simulate the engine failure. So already we have a recipe for confusion. Next problem is regarding a real engine failure procedure once again taught by flying schools. Identification is by `dead side dead leg` a method tried and trusted throughout the years. But then students are taught to close the dead engine throttle to confirm you have the real dead engine.
But hang on a second. Apart from only one aircraft POH (and I think it may be a Beech Baron) I have yet to see published in any manufacturer's AFM or POH that confirmation by pulling back the dead engine throttle is required. In fact, confirmation you have the correct dead engine by throttle pull back, was only applicable to a four-engine aircraft. Dead side dead leg still applied; but which of the two engines on that side was the crook donk? After all there is a swing towards that side.
Now this is where the confirm with throttle gentle closure came in. If you pull back the wrong dead engine throttle the yaw will increase significantly whether you are flying a DC4, a Lancaster bomber or a Super Constellation. That is the real story behind "confirm with throttle closure." It was never meant to apply to a twin engine aircraft in my time and that goes back a few years.
With the proliferation of turbo-prop aircraft on the Australian register, where some have auto-coarsen or autofeather, a pilot instinctively reverting to his flying school teaching of throttle closure to confirm would likely immediately find himself in serious handling trouble of his own making. That is because of excessive drag, since throttle closure would negate the auto-coarsen and auto-feather system. Thus leaving the aircraft with potentially disastrous drag on one side. This is one possibility for the investigators of the C441 Renmark accident to consider.
What is currently taught during initial twin training at a flying school in terms of practice engine failures at low altitude, may be quite different when applied to a twin turbo prop. This is especially relevant if the instructor has never flown a twin turbo-prop which probably applies to a high percentage of ME instructors.
In short, there is no need to double confirm which engine has failed following an engine failure of a twin engine aircraft. The instant yaw towards the dead engine is confirmation enough. This is especially on take off where the time taken going through the lengthy list of drills as taught at flying schools, before the pilot finally gets to feather the dead engine prop, means drag from its windmilling propeller can lead to drastic airspeed loss.