A common reason is the installer is using 2 female MPO connectors to extend an MPO network. All Fiber cables transmit pulses of light instead of electrical signals, so the terminations must be precise. Fiber optic connectors must align microscopic glass fibers perfectly in order to allow for communication. In general, fiber cables are equipped with male connectors and the couplers have sleeves to guide the ferrules to make a connection. For MPO the connector is available without guide pins (female) or with guide pins (male) to align the fibers since the couplers do not have sleeves to guide them. MPO adapter is just a shell to hold two connectors together.