So much misinformation in the world - its a wonder we have survived this long....
I have a single LNB dish and can have 8 boxes hooked up. You just need a multiswitch. They are around $50. You run the two sides of your single LNB to the multiswitch and it splits off to your TV receivers. Witha multiswitch, you can even piggyback cable or antenna TV signal on the same coax and use a "diplexer" on the TV end to split it back out.
You do NOT need extra dishes, or even a dish with multiple LNBs. The extra LNB dishes come into play if you want to access more then one satellite. Such as oddball programming like Al-Jezeera, NASA network, or HDTV signals.
Little more info - there are several transponders on the 101 (regular DTV) satellite. They are divided into odd and even transponders. If you try to access an "odd" channel, it goes to the odd transponder, "even" to the even. Its actually a polarization issue - but this is the easiest way I can explain it. That's why you need to run 2 coaxes from your dish. This way you can watch odd and even channels at the same time.
You should also run RG-6 from the dish to the multiswitch and to each receiver. The rg-59 smaller cable with a ton of splitters (like cable tv does) is usually not sufficient. The way the boxes and receivers determine odd or even is through line voltage. So, the receiver sends 18v to the dish - the small cable and long length with splitters may drop the voltage to below 13 - in which case the dish sends the wrong "odd" or "even" signal and you don't get your channel.
That is the simplest way I can explain it.