Here are the steps to remove duplicates from MBOX files using MacUncle Duplicate Remover.
Start MacUncle MBOX Duplicate Remover.
Add MBOX file using Add File(s) or Add Folder(s).
Now, choose any folder from the list as per the requirement.
Select any options from "Use Selective Duplicate Settings". Also, select the removal procedure "within or Accross" the folder.
Set a Date Filter to remove duplicate from particular date range.
Press the Export button to start the process of deduping MBOX files.