Edited my previous post. If the installer had done it right the first time, your SD receiver swap to HD would have been as simple as swapping receivers.
Yeah, I think that additional, extraneous 129 dish had to do with look angles. Anyways, all I want is HD for my Slingbox! By the way, the Slingbox works great for anyone wanting to get one. I got the 350. Works perfectly.
The installer should have used a DPP44 if you needed two separate dishes. Try contacting DIRT, show them this thread, maybe you'll get a free visit since they didn't do it right the first time.