If it was one continuous motion, without a second intentional swing or push, then it is a legal shot even if it hit your racquet twice in the one swing. It is also your call to make and not your opponent's.
The rule continues to clarify that: “Two hits occurring during a single continuous swing are not deemed a double hit.” Except where noted, answers are based on the ITF Rules of Tennis and USTA ...
No, the let rule has not been changed and lobs out of the court are still a loss of point. However, a major change passed by the Board at the May 2008 meeting is that a “carry” or “double hit” is now a legal shot providing that the player uses a continuous motion, and hits the ball before it reaches the screen.
Rule 24.b. of the ITF Rules of Tennis says that a player loses the point if “The player does not return the ball in play before it bounces twice consecutively . . . .” So, in our match, if the ball bounced twice before my opponent returned it, she lost the point.
Doubles In doubles, you and a partner play against a team of two players on the other side of the net, using the full court between the baselines and the doubles sidelines. If you are on the team that serves first, either you or your partner may begin the match by serving the first ball.
More Tennis Rules Double Hit images
making one return, only one member of a doubles team may hit the ball. If both of them hit the ball, either simultaneously or consecutively, it is an illegal return. Mere clashing of rackets does not make a return illegal unless it is clear that more than one racket touched the ball.
7. ALTERNATE HITTING IN A DOUBLES RALLY. Doubles partners must alternate hitting balls in a rally, no matter where the ball lands on the table. 8. VOLLEYS are NOT ALLOWED . Can you hit the ball before it bounces in ping pong? No. In regular tennis you may “volley” the ball (hitting the ball before it bounces on your side of the net).
since 1970's double hits are allowed if it is in one motion. for some reason a lot of people don't seem to have caught up with this though.