During some recent work we highlighted when trying to add an exception from the monitors window that we had numerous duplicate policies and it turned out this was because there were non-shared policies with the same name as a shared policy. As there was no way to distinguish between these I suggest putting a marker against these to identify them as shared or non-shared, and perhaps even a link to show which groups the policy is assigned to. The other alternative as disucussed with Symantec support engineers would be to force the SEPM to require disinct policy names for non-shared policies.
Another issue is that by design the SEPM apparently does not remove references in the database to non-shared policies if the group which it is assigned to is deleted, or if it is replaced by a shared policy. Again some sort of tidy up on this or marker in the database to say it is unused would be a good idea.
We had to get a special tool from to tidy up the database as a result of a bug in a very old version which had allowed this to happen unoticed over a long period of time.