A dual magnetron for plasma sputtering in which two distinctly different magnetrons are mounted on a common plate rotating about a central axis in back of a target. At least one of the magnetrons is switched on and off by changes in chamber pressure or target power while the other magnetron, if it does switch, switches in complementary fashion. When the two magnetrons are mounted at different radii, the switching effects a effective movement of the magnetron such that different areas of the target are exposed to a sputtering plasma. In particular, a small unbalanced magnetron may scan the target edge to produce a highly ionized sputter flux and a larger magnetron positioned near the center can be switched on to clean sputter material redeposited on the target center.