A C-Band LNB that has two outputs for two recievers. Or a "Loop out" (F connector)on the first reciever to the second one. Option one shares the satellite, option two shares the transponder.
With a dual output lnbf, you can also feed a 3x4 switch for up to 4 receivers or a powered or unpowered 4x8 switch for up to 8 receivers in the house. See how much money you could spend ?