I give up trying to explain it.........
BTW, yes you would have less chance of having ONE engine failure on your single engined CFM56 aircraft, than on a similar CFM56 twin, but I don't want to be on it thanks.
Okay, one last try.
Forget engines, let's look at hydraulic pumps.
Say each engine has 2 hydraulic pumps, so on a 2 engined aircraft there are 4 engine driven hydraulic pumps, and on the 4 engined aircraft there are 8 pumps.
Now the 4 engined aircaft is probably safer, but there MUST be more chance of ONE hydraulic pump failing on the 4 than the 2.
But LESS chance of losing ALL pumps on the 4.