Managing several Outlook PST backups can become confusing when the same emails are saved in different archive files. For example, one PST may contain an older mailbox backup, while another includes emails exported after a migration. Combining or reviewing these files can reveal repeated messages and make it harder to identify which records are unique.

The first step is to check the PST files separately and determine whether the repeated messages exist within individual folders or across different archives. Comparing fields such as sender, recipient, subject, message date, and body can help distinguish genuine duplicates from emails that only look similar.

For this task, SysInfo Outlook Duplicate Remover  supports processing multiple PST files in one operation. It provides options to search for duplicate items within selected folders or across PST files, preview mailbox contents, and apply criteria for identifying repeated emails. It also supports cleanup of contacts, calendars, and tasks. Official product details

Users can choose how identified items should be handled, including moving them to another folder, sending them to Deleted Items, or deleting them permanently. The software can save the cleaned mailbox data to a new PST file, keeping the output separate from the source archives.