You COULD have a situation of very bad luck, where both engines on the 2 engined aircraft failed really early, and the engines on the 4 engined aircraft never failed, just luck.
However, there MUST be more chance of ONE engine failing at any time on the 4, than ONE engine failing on the 2.
There is however more chance of ALL engines failing on the 2 than the 4.
IF you still don't get it, forget aircraft, it is just logic.
I am about to head off to work now.
During my drive to work in my car, IF a semi trailer was to follow me over the exact same roads, there is (I hope
) MORE chance that he will get ONE flat tyre with his 18 tyres, than I will get ONE in my 4.
Mentioning both failing - the BASI accident report on the Chieftan double engine failure in South Australia is a worthwhile read in relation to piston engine reliability.
Woomera