An ion implantation system has a mass analyzing magnet having interior and exterior region and defining a first entrance, second entrance, and an exit. A first ion source defines a first ion beam directed toward the first entrance along a first beam path. A second ion source defines a second ion beam directed toward the second entrance along a second beam path. A magnet current source supplies a magnet current to the mass analyzing magnet. Magnet control circuitry controls a polarity of the magnet current based on a formation of the first or second ion beam. The mass analyzing magnet mass analyzes the respective first or second ion beam to define defining a mass analyzed ion beam along a mass analyzed beam path. At least one shield in the interior or exterior region prevents line-of-sight between the first and second ion sources. Beamline components modify the mass analyzed ion beam.