Description of problem:
If, for whatever reason, multiple content sources contain the same errata, the errata shows up multiple times in the Promotions > Errata view

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.  Add RH provider; sync 6.1 standard and optional content 
2.  Promotions > Errata > All
3.  Look down the list; you'll probably readily see the dupes, but if not, click around until multiple lines end up highlighted.
  
Actual results:
We're gettind duplicate results, presumably because the same errata is used by multiple content sources

Expected results:
Uniquify the errata list

Additional info:
This also provides some evidence that we're not sorting these in some sort of predictable order, but not too concerned there, right now.