Twin engine training is quite safe as such. It is the idiot instructors who are likely to get you killed. Those that cut the mixture control to "simulate ' engine failure at low altitude or on the runway are the most dangerous of them all.
For some strange reason it seems that Australian flying school instructors are the hairy chested ones that cut the mixture control. In UK the practice of mixture cuts is banned and in USA there is an NTSB warning against the practice as too dangerous. But not in good old OZ where only wimps use throttle closure to simulate engine failure. Youse have gotta be realistic matey, is the mixture cut motto.
Before embarking on a twin endorsement or initial twin training as a student, ensure you know exactly what method of simulated engine failure your instructor prefers to use. If he says mixture control simply offer to break his arm if he touches the mixture control - or just walk away and find an intelligent instructor - not a mixture cut cowboy.
Pilots and students have been killed using mixture cuts and in every case it is the instructor that started the chain of events that led to crash -burn-die a painful death.