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Not sure how it works on Leothreads but normally on Hive: Only the duplicated one should be deleted.

If it removed both, you either mistaken the duplication, or it wasn't indexed yet? Hope someone from Leo Team checks if there's a bug.

Thanks a lot for your answer!!

Yes, the indexation not having taken place yet could be what happened, because I've seen those messages show as published (after the 4th refresh).