VegasVoomer -- It appears you are using a second dish at 61.5 to receive HD and/or international programming, and possibly some locals depending on where you are. You didn't mention how the two cables combine into one, which could be through a DP Plus Twin on the Dish 500, or maybe 3 cables into a switch, etc...
Woljr -- As Scott said, you need to have the same satellite or satellites connected to each Sat port on the back of the ViP 622 for it to work (correctly); but more importantly, so that you can take advantage of all of the ViP 622 features. Such as, using TV1 to watch one program, while TV2 is recording another program, or maybe someone else in the other room is watching a different program using a separate UHF remote.
Scott is correct that you do not need two dishes for the ViP 622, however I suspect you may be needing more information.
You may have a single dish antenna that can pick up 1, 2, 3, or 4 satellite orbital locations, or you may have multiple dishes to do the same thing. Depending on how many satellite orbital locations and what type of LNBF's are being used, you may be using one of several switches. Which satellite orbital locations you need to receive depends on which programming packages you subscribe to, such as, normal programming, locals, HD programming, International, and etc.... All of this will depend on how you connect this dish or dishes to your receiver.
You may have 2 cables running from an LNBF or a switch (DP34) with one cable going to each Sat Input (Sat 1 & Sat 2) on the back of the ViP 622. If a DPP44 switch is used, you can run a single cable to the back of the 622 and then split the signals using a DPP Separator. A standard splitter will not replace a separator.
Respond with what packages you subscribe to, or desire to subscribe to, as well as what city for locals, and what type of dish, someone will respond back with more info that may be helpful.
Bottom line: If you have a ViP 622 and only have a cable going to the Sat 1 or Sat 2 input, I would say your installation has not been completed.