Rated 4 out of 5 stars

per happyboy1992 el set. 28, 2011 ·

It'd rather good add-on; however, I cannot see duplicated emails by using left click

This review is for a previous version of the add-on (0.1.10). 

per Thorsten W. Schmidt (desenvolupador) a set. 28, 2011 ·

You need to do a right click on a folder. There you can select 'Remove Duplicate Messages ...'