Except 1903 Wright flyer, are there any other airplane using one single engine driving two coplanar propellers?
Coplanar means push-pull and coaxial designs are not in the question's frame.
Tilt rotor aircraft that able to fly with one engine driving two rotors in case of an engine failure are also outside the question's frame.
Edit: I recently came across an example of such a configuration, in this video mentioning the André Starck's AS-37, powered by a 60hp Citroën GS engine driving two propellers.
(source)
(printscreen from above video)