Generally speaking no.. But it depends a lot on the dish and the receivers (DirecHDTV SWM I am not sure of so someone else will have to describe that service)
On the antenna the deciding factor is a device called and LNB, if it's a SINGLE (just one cable connection) then see the above statement.
IF it's a DUAL (two cable connections) you can run TWO cables one to each receiver, and it will work.
If you wish to add a 3rd or 4th or up to eight total.. You put in the proper Digital Equpmant SWITCH (not a splitter but a switch) and it works.
What is the differnce between a splitter and a switch?
Spllitter simply divides the signal, each receiver gets 1/4 to 1/2 (if it is a 2 way) depending on how the splitter is made.
Switch selects right or left hand polarization, Which Satallite and such and properly delivers the desired group of transponders to the receiver.. Satellite transmissions actually have TWO signals on each frequency, the receiver can not tell them apart. but the antenna can because the signal is transmitted in a sprial or circular pattern.. Like the threads on a screw,, and the Right Hand Screw/Signal screws into the right hand Nut/antenna.. A left hand Screw/Signal, into a left hand Nut/Antenna.
But like with screws, IF you try to screw a RHT into a LHT, no joy.