Why do light twins , including commuters, have two engines? Because they need BOTH of them.
At best they're the equivalent of a single engine a/c with half its engine mounted 'over there' and the other half mounted 'over here'. This means that an engine failure is constrained to be more like a 'partial' failure of the (single) engine.
Like single, a partial failure may leave you with enough power to maintain flight......or it may not. Instead of having sufficient excess of power to guarantee performance (two engine or FAR25 a/c) you're now in the situation where you just barely have enough **IF** the a/c is configured optimally. BTW, gear down, flap down & prop windmilling is not 'optimal'....