A system for depositing substances onto a deposition surface can comprise a first contact spotter comprising multiple spotting orifices fed by multiple fluid inlet conduits such that the first contact spotter is capable of depositing multiple spots of different substances onto the deposition surface simultaneously, and a second contact spotter comprising a second spotting orifice fed by a second fluid inlet conduit. The system can also include a positioning device adapted to alternatively position and seal the first contact spotter and second contact spotter on the deposition surface at an overlapping location.