I have found a plane, that had both a pusher and a tractor propeller, which flew for the first time over Cotroceni airfield, Bucharest, Romania, on June 17, 1910. Likely there are other planes like this that flew before.
Vlaicu I plane during construction
Newspaper article about Aurel Vlaicu's first flight July 17, 1910
Source: A Vlaicu I - Wikipedia