Multi-mode fibers are better at gathering light. The larger core size allows transmission of a larger range of the spectrum. Multi-mode fibers can not travel as far as single mode, and they have less bandwidth.
SC to LC
MilesTek offers many different duplex cables that allow you to duplex LC and SC connectors.
ST to SC
MilesTek offers many different duplex cables that allow you to duplex ST and SC connectors.
ST to ST
The "Straight Tip" 2.5mm fiber optic connector is typically used in Multimode fiber optic capacities.