After selecting a diagram you can duplicate the elements that are visible on this diagram. The routine will make a package for the originals, duplicate the package and eventually add some extra functionalities like:

• Keep the original elements (as available in the diagram) are kept in the original package after running this functionality (otherwise the elements are copied back to their original location)
• You can create a baseline of the elements in the original package for release reasons
• Creating a trace association between the original and the baseline for easy navigation in the traceability window for example.