I'll take a stab at this, but may need other input to set me right. A dual LNB dish will allow you to connect two DBS receivers (the only way to view two different DBS signals) I don't think it is possible to "split" the signals prior to the receiver. The higher the number and letter in the model number,(SONY) the later the model and more advanced. Local capabilities currently are divided between previous cable subscription and local antenna reception. DishNetwork offers an adhanced version which provides local reception via an additional dish (antenna) to intercept the local signal.(soon all providers will offer local or network signals to all subcribers)
Lastly, DO YOUR HOMEWORK. The deals are out there and the retailers are bending backwards to get your business. (Have you seen the advertisements during NFL broadcasts, which are probably broadcasted to you on a cable signal?) Good luck!