An apparatus including a drive; a movable arm assembly; a plurality of sets of end effectors; and a controller. The end effectors are connected to the drive by the movable arm assembly. A first one of the sets of end effectors includes at least two of the end effectors, where the drive and the movable arm assembly are configured to move the at least two end effectors substantially in unison from a retracted position towards an extended position towards two different respective target locations. The at least two end effectors are at least partially independently movable relative to each other on the moveable arm assembly. The controller is configured to detect an offset of respective substrates on the at least two end effectors and adjust movement of the at least two end effectors relative to each other prior to placement of the substrates at the respective target locations.