This theory about twins versus singles and statistics goes around and comes around...
It's down to reporting:
Engine failure in a single: very likely to be reported, quite likely to end with a happy outcome (low stall speeds, tend to fly in good weather, etc);
Engine failure in a twin: much less likely to be reported, because it usually ends with a landing at an airfield, usually (but not always) with a happy outcome, but when its an unhappy outcome it tends to be serious (higher stall speeds, energy proportional to V squared, they more often fly in bad weather, etc).
A piston twin in the hands of a well-trained and able pilot is a MUCH better option than a piston single...