table tennis racket rules
2.5.2 The ball is in play from the last moment at which it is stationary on the palm of the free hand before being intentionally projected in service until the rally is decided as a let or a point. 2.5.5 The racket hand is the hand carrying the racket. 2.5.6 The free hand is the hand not carrying the racket; the free arm is the arm of the free hand. 2.6.1 Service shall start with the ball resting freely on the open palm of the server's stationary free hand.
The rules clearly establish a free hand and a racket hand.
9.3 For the same reason he cannot make a good return by throwing his racket at the ball, because the racket does not “strike” the ball if it is not held in the racket hand at the moment of impact. However, a player may transfer his racket from one hand to the other during play and strike the ball with the racket held alternately in either hand, because the hand holding the racket is automatically the “racket hand”. Therefore it is assumed that it is illegal to use two racquets as you are allowed to switch between hands.