Two of anything has got to be better/safer than only the one - common sense.
If an ECU is going to fail on any set day/night in the future, then it is more likely to result in serious damage/death over a built up area, in a single than if it happened on a twin.
During my time with police ops I lost an engine on two occasions - one during the day where a compressor blade went walkabout and the other engine failure was a surge at night. Both of these incidents were over built up towns/cities. Both resulted in a fairly undramatic landing around the outskirts to resolve the problem. A single would have put a whole new perspective on matters!!!
PS: How on earth can one compare Police Helo Ops with " Nuclear Security" whatever that is???
Sasless has me on Peanut Gallery alert so can someone else ask him what a typical task is during a Nuclear Security job?????