China has apparently copied the Russian Su-30MK2, and is operating it as the J-16, claiming that the aircraft is of Chinese design. More unauthorized pictures of the J-16 are showing up, via Chinese with cell phone cameras and Internet access. It's pretty clear that the J-16 is a copy of the Su-30MK2.
Russia and China jointly developed the two seat version of the Su-30, as the Su-30MKK in the late 1990s, and, a decade ago, an upgraded version (the Su-30MK2). China has received about a hundred legal Su-30MK2s, but now nearly identical J-16s are showing up.