Stellar Merge PST software can merge as well as join all your Outlook PST files quickly. In the PST merge process, it combines all the matching folders from different PST files into one PST file, a new, or an existing one. Whereas, when you join the PST files, it creates several hierarchies of folders within the joined PST file. Thus, as per your requirement, you can either merge or join the Outlook PST files. This software removes same emails from the new PST file during the merging process with 100% guarantee. It offers you the option to remove duplicate emails in three ways: by Text, Subject, and Sender Email options, which remain checked by default for your benefit. You can disable them by unchecking the provided options.