So you have only one coax cable, with minimal protection > 90 DB and is no more than 30 meters fitted to a  Single-Lnb and you want connect it to 2 Receivers or one Twin-Receiver indepently.

Solution: Mount a Twin-Lnb and connect them both on to the "Stacker". Mount the excisting cable to the  "Destacker", then you have 2 endings for 2 Receiver or one Twin-Receiver to use them independently.