Then you should be good to go. The fact that your two TV locations had Directv running at one time clarifies much. The older SD round dish has two lines running from them and each one probably served one of your TV locations. What will probably happen is the tech will use one underground line to connect the new dish to a DirecTV approved splitter (and power inserter) in the attic or elsewhere. The SWM (Single Wire Multiswitch) makes DirecTV installations more like what you may have seen with cable.
One issue that may come up = the new dishes use a 2" pole. The older poles are smaller. I don't know whether Directv techs use or have pole adapters that allow mounting the larger dish on the small poles....so the tech may want to install a new pole. IF the existing pole is pretty firmly installed you can clamp a new pole to the existing one rather than dig a new hole etc.
IF the tech decides to kick in more cable......there is a possibility he will find your HughesNet cable with his shovel. Try to find where that cable enters the building. Also your telco line may be shallow near the building so add these to the list of things to observe and test during the installation.
Report how it goes,
Joe
Good point about the difference in pole size, thats something I forgot about, lets hope thats not an issue for Blues.
Personally, if he has to place a new pole close to the old one, let him, go out at a later time and cut the old one down ...