There are philosophical differences between flying singles and twins. as well as philosophical differences by the operators that use both.
In a single an engine failure is an emergency landing, in a twin -in most flight regimes-it is not.
I've flown with co-pilots that had alot os single engine time and they really struggled with CRM. If I had the choice I would sooner have a competent low time pilot as a co-pilot than a high-time single engine pilot.
The twin engine world is usually a night/IFR or Offshore environment. In a single there are few systems to manage while in most twins the pilot is a systems manager.
One cannot compare the military to civilian. The military keep only those that are able to progress in the prescribbed sylybus and have the best training avialable. They are also constantly monitored.
Engine failure rates for turbine engines are around 1/100,000. In a twin you are twice as likely to have an engine failure, granted the consequences should be less severe.
Now if we are talking about flying a Bell 212 VFR or a turbine single there is really not much difference.