You can use a single line off the dish if you buy a stacked LNB. Or you can use a single line from a stacker (which gets both sides of a normal LNB as input). In either case you may or may not need to split it at the R15 installation point for the two inputs. The advantage of stacking is that the stacked signal can be split indefinitely (up to signal strength limits, of course), which is why a lot of apartment buildings with a single community dish use them (otherwise each unit would have to have cable runs all the way to the dish, or at the very least a nearby multiswitch). It's a bit expensive for the home user considering the benefit isn't as great. But if I were doing my setup over again and all my receivers had built in stackers, I'd probably go that route (so I could have re-used the existing wiring from cable TV).