YOU SAID:
A330/A340 had a wing.
Now A330 and A340 have another wing.
A340-500 and -600 have yet another wing.
And Emirates' A340-600s will apparently have yet another wing (for more TOW).
The A340-100, 200 & early 300 all missed their perfromance guanantees by a long shot when the aircraft delivered. Then, AIRBUS ( with egg on its face ) instituted a Product Improvement Programe to try to shore up these shortcommings - in particular they reskinned many of these birds to integrate the "add-on" localized aerodynamic fixey's into the basic and stable aircraft definition - like adding the low drag Boeing styled rain-gutters, & new wing aerodynamics to solve engine/wing shock drag/buffett.
Yet - the newest A330s have a new recontoured leading edge as well ..