Which receiver do you have?
A dual tuner receiver should have a SEPERATOR on the back of it to seperate the two stacked bands of signal from the lnb's.
Feeding a single TV from any receiver should have NO cable splitters in the system, they will degrade yout signal strength out of the receiver not make it better.
You have only postulated a situation to us, not detailed what your system looks like.
Please detail what you have from the dish to the TV and everything in between.
Given that we have no idea how your system is setup, we cannot offer any more intelligent help than you already have.