What is the rationale behind "One engine - Two propellers" configuration?
It looks as if they rotate in opposite directions. This eliminates prop torque, which should improve handling, especially at low speeds.

On the other hand, you are right with your impression that it adds complexity, but at least it is not completely useless.

Asymmetric prop failure is indeed an issue and will markedly reduce handling qualities, and for that reason both props are close together, so if one is left, the yawing moment should be manageable if the craft flies fast enough.

Putting a single prop in the center would present it the messy flow coming from the unfaired cockpit and engine, so placing them left and right should improve inflow conditions. They are still close enough so the tail is in the prop wake and will have improved effectiveness at slow speed and on the ground. On the other hand, the outriggers will create additional drag, and it is hard to say if this arrangement will have performance benefits.