Rated 5 out of 5 stars

Από τον/την Jonathan Watt στις Μάιος 10, 2019 · μόνιμος σύνδεσμος

Works well for me.

@Konrad65 @ChrisInVT I needed to open the preferences for the add-on via the menus:

Tools > Add-on Preferences > Remove Duplicate Messages

I then unticked "Size", and then it found duplicate messages.

I believe this is because the size of the duplicates is different to the originals because new headers were inserted into them.