You can use an HDMI splitter (NOT a coax splitter) to feed one Wally's signal to two TVs. That's what we do, even though our Tailgater 2 has two separate outputs for two receivers. I just don't want to run a second line into the trailer from the dish.
It's my understanding that what someone else said earlier about two receivers having to watch content from the same satellite (if using the dual output from the dish) is true, but I haven't tested that myself. Besides, our trailer is so small that one person would clearly hear what the other person was watching anyway. LOL!