The law changed in May of this year and now says:


It shall be a ‘fault’:


13.3 If in play, the shuttle:


13.3.7 is caught and held on the racket and then slung during the execution of a stroke;

13.3.8 is hit twice in succession by the same player. However, a shuttle hitting the head and the stringed area of the racket in one stroke shall not be a ‘fault’; ".

So a double hit is now a fault unless the shuttle hits the frame and strings in one stroke.