Description of problem:
Systems -> <system> -> Software -> Packages -> Install page lists many duplicate entries for packages. A duplicate entry is created for every version of the package, regardless of if that version is available in channels this system is subscribed to or not. So you can have only 1 version available to this system but 19 other versions in other channels, and there will be 20 entries in the list to the same 1 package that is actually available.

Version-Release number of selected component (if applicable):
spacewalk-java-2.2.52-1 and higher

How reproducible:
always

Steps to Reproduce:
1. Go to page
2. See many duplicate packages 

Actual results:
See many duplicate packages 

Expected results:
Entries should be unique and all entries should be actually available to server.

Additional info:
It was broken in commit f5e644f6d0f5c194081073fd6a850918f393dea9