Which dual tuner sat receiver?
I will assume it is a DISH 622/722 type box. If that is the case, you may be out of luck. The second output is strictly RF and requires an analog TV tuner at the receiving end. There are a couple of ways to do this, but maybe not directly. You couled hook an old VCR into the system. You would then feed the video to the projector, and the audio to an amplifier. You could do the same with a TV, a DVD recorder, or whatever else you could find that had an NTSC tuner. Other than that, you would not be able to do what you want here.
Personal opinion: I think you may be disappointed in the video quality of the projected signal. An RF connection on standard NTSC is the worst possible connection in terms of quality. Blowing it up with a projector simply emphasizes all the problems. You might be better off looking at an HDMI splitter. It would force you to display the same signal to both TVs, but the quality would be immensely better.