Nothing has changed in this area – the fixes for this release were related to how tags are printed to files during the export process.
We’ll put the the duplicate detection here through some testing and update the ticket with the results unless we can’t reproduce, in which case we’ll let you know if we’re not able to reproduce.
I assume you’re just exporting to a folder, making changes to the playlist, and exporting again with the expectation that files which were previously copied won’t be copied again, but let me know if there are any additional requirements you’re expecting here.