Content type set - duplicate content type

When configuring the portal, it's sometimes required to split an existing content type which is defined for a combination of model/object types, into content types per model/object type.
It would be nice, if we could then just duplicate the existing content type and adjust the mapping.

To avoid impact on the existing factsheets, those properties referencing the 'old content type' should be extended with the newly created via duplication.

The default factsheet for the newly created content type should initially be equal to the factsheet of the original content type.