Are twins statistically safer than singles?
The unanswerable question. You seem to have strayed from "engine failures" to a wider view of incidents. Even "bolkow" above hasn't stuck to engine failure as a cause - but was the gear failure caused by too much torque from 2 engines ?
The only facts I know are that 2 engines cause more stress for related systems, and that the advances made in engine reliability over the past 40 years have still not made it through the system with a decent set of regulations for SEH. (In the UK & Europe). There is still a heavy bias against SEH when the stats and the reality don't demand it.
Can all twins at all weights operating at, say, 750ft AGL safely depart the area when a power unit fails ? No. Can the same machines safely auto to the ground from that height ? No.