Yes, there are many methods to remove duplicates from MBOX files without disturbing the folder hierarchy by using a specialized tool like
SameTools MBOX duplicate remover tool. This tool scans all folders, detects repeated emails from MBOX files based on sender, subject, date, and message content, and removes only duplicates while keeping the originals intact. They preserve attachments, folder structure, and metadata, ensuring no important information is lost. The tool handles multiple duplicate MBOX folders and large mailboxes efficiently and eliminates them without downloading any application. It has an intuitive user interface suitable for all non-technical users. A free trial is usually available, allowing you to review duplicates before final deletion for a completely safe cleanup process.
Visit here:
http://www.sametools.com/duplicate/mbox/