You can do this with the advanced filtering option in excel 2011 on a mac.
- Highlight the items to be sorted
- Go to Data->Advanced Filter -Select either filter the list in place, or copy the data to a new location (I always copy to a new location, because, Excel.)
- If you have some filtering criteria, enter that in the criteria range box, otherwise leave blank to filter everything
- check "unique records only"
- press OK.
Good luck.