Remove duplicate mails does not always find the duplicates
I have a big folder with duplicate messages, it's a local maildir account. Selecting all mails and then Message->Remove_duplicate_messages, it doesn't find any. But selecting 2 of the duplicates I know, then it finds it. What can I do? Selecting the 2 duplicates and some others sometimes works and Evolution can find the duplicates, but even selecting some more mails like 10 mails including the duplicates, it doesn't find them anymore.
I have many duplicates after moving mails from one account to the other, which was interrupted with some mails copied, some moved and some not. After moving the left mails again, there have been lots of duplicates.