Two receivers, one motorized dish
I was curious about this setup also, so I just tried it now.
I have one motorized dish running to one receiver, and then took the Loop Out from the back of that receiver and ran it into another receiver.
Then I turned them both on and set them to the same satellite. This worked fine, I was able to pick different channels off the same satellite at the same time (even from different transponders...as long as they were on the same satellite it worked fine).
When I tried to move to another satellite with one of the receivers, sometimes nothing happened, other times the dish actually did move, but when it got to that satellite, the other receiver triggered the motor to move back...and this tug-of-war would repeat over and over (maybe a good way to burn out a motor?)
However, if I put one of the receivers on stand-by, then I could move the dish to another satellite without difficulty. This worked with either receiver: as long as one of them was on standby, the other receiver could control the motor.
Then after moving to another satellite, I put the current receiver on standby and took the other one off standby. Initially, there was no signal, since the dish was pointing at the wrong satellite. But if I just selected the channel again (or picked another one), that triggered the motor to move back to the satellite it had been on, and it did so.
So...it is possible to have two receivers with a motorized dish, you just either have to have one of them on stand-by (especially when you want to move to another satellite), or keep both of them on the same satellite if you want to use both at the same time.