After importing several thousand mails, I have now two different mails that are marked as duplicates of each other. They have shown up with other, real duplicates in the dupicates smart group, but the Apple Script that deletes all duplicates despite one did not delete these.
It seems that Apple Script could identify the differences (different mail title / Betreff; different creation dates etc.).
I would like to get rid of the identification as duplicates, and I am in doubt about the credibility of the decision making.