I don't see why, but Dish generally does not believe we know what we are doing and wants to have a tech do the install, making sure both tuners are connected, the right sats are being seen, etc.
I convinced Steve with executive resolutions that I did know what I was doing, and he succeeded (about a year ago) in Dish'n... Up two 612's for me at $25 shipping cost, each. 2 year commitment of course.