I have never flown all the way through (done DXB-KUL/KUL-DXB legs on the 408 and 409 a few times), but have never noticed anyone staying on the plane after I disembark in KUL, or announcements for onward pax to MEL to do so!
For the reverse, I am usually among the last to board in KUL so don't get the chance to see if MEL pax are still in their seats to await those joining the flight in KUL.