This is still the same in the latest v216 build, which is disappointing when work was actually done on the playlists 
@support Can you clarify if this got fixed in the recent 216 update please? and perhaps this would be better in the support forum, as they are bugs rather than feature requests, as I had initially thought. Thanks.
For me exporting the same files to the same folder, with no external changes, results in a full export of the same files, even with the duplicates flag selected.