I may have it ass-backwards, or back-asswards, but the 6397 is the HD version and the 8632 is the SD version of your local channel 3.
The channel 003-00 doesn't exist, but is just a re-mapping of either 6397 or 8632 to its actual Over-the-Air channel number (3). I believe all new receivers can do this, but some earlier models will not.
Okay, which channel is mapped to number 3? In the menu, I believe under HDTV Preferences you can select if HD channels take precedence over SD channels or not. Since your 003-00 is showing HD, you must have local channels set for HDTV when available. You can also select that your 622 use regular Over-The-Air reception instead of mapping 6397 or 8632. I haven't tried this since I am unable to pick up any local channels here.
So if you do a search for a television program that happens to be on Channel 3, it will show up 3 times, once as 003-00, 6397, and 8632. And if channel 3 was also a SuperStation, then it would be listed 1 or more additional times, depending on how many channels you were picking it up on. There may be a way around this, but it hasn't bothered me that much.