If sat signal falls below a certain level, the receiver may halt the recording and start another when the signal comes back to acceptable levels.
Check the cable to the offending receiver and make sure it has good connections and that the stingers (center wire) are proper length. I believe they should be 1/4 inch beyond the end of the ferrell. Too long can short out the connection, too short can fail to make a connection.
I'll bet it is further from the dish (in terms of cable length) than the one that works properly.
I had my principal receiver fed by a cable running around my house going back through the house to the receiver near the wall where the dish was located. When I309384253laced that line with a direct line through the wall to the primary receiver my signal level went up 10 points.
Another way to check would be to temporarily swap the receivers, if the trouble remains at the problem area, you know it is cabling or switch related.
If it moves with the receiver, the receiver is probably faulty.
If it is not the receiver, the first thing to do would be to peak the dish to get the absolute highest signal. That may solve the problem in itself.