how can I hookup two dish receivers to one TV using one set of input.

Solution
If I read it correctly - OP wants to split the signal from the dish itself onto two different receivers. This is nnot going to be easy on two points:
- the receiver itself provides power to LNBs inside the dish
- simple "coax selector" would introduce way too much noise into already noisy signal

Long time ago, simple splitters could be used for that, but I am not sure this will work with current gen receivers.
If I read it correctly - OP wants to split the signal from the dish itself onto two different receivers. This is nnot going to be easy on two points:
- the receiver itself provides power to LNBs inside the dish
- simple "coax selector" would introduce way too much noise into already noisy signal

Long time ago, simple splitters could be used for that, but I am not sure this will work with current gen receivers.
 
Solution