Sims etc
Just a note that may or may not be applicable. FAA and I'd assume the CAA follows a similar criteria in this regard, does not require simultaneous dual engine cuts throughout the flight envelope. So, there would likely be zero flight test data with which the sim design staff could rely on for this failure case. Behavior of the rotor and aircraft in stall conditions following a dual cut can be highly non-linear, thus very possibly* beyond the ability of the existent stability and control math to predict with any accuracy.
*If one said " probably". I for one wouldn't disagree.