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However , the plane in question seems to belong to the US Army. If you make a focus on the undersides of the port wing you can notice the "ARMY" inscription. Also there is a small number 2778 on the rudder. The US stars can't be seen because of the slipcover IMHO..
The twin engined bi-plane in RAAF markings is a DH.84 not DH.89. Shape of the wings is very different on both types.