Diplexers must be used in pairs, and there should only be "wire" between them (barrel connectors work fine - just not splitters).
My preferred way to handle situations like yours is to keep DIsh / antenna separated from distribution networks. So, I would run coax from the TV2 output directly to the room where the CECB/other satelite receiver is going, and join the TV2 and antenna there.
My preferred way to handle situations like yours is to keep DIsh / antenna separated from distribution networks. So, I would run coax from the TV2 output directly to the room where the CECB/other satelite receiver is going, and join the TV2 and antenna there.