You can also try the KDETools PST Merge to merge archived PST files in MS-Outlook in any Version of Windows and Outlook. It Combines PST files without any duplicates PST items. It Consolidates various PST files such as Emails, Contacts, Calendars, Tasks, Notes and all. It merges without any duplicates PST files in MS-Outlook. Demo Version is also available. Preview option is available to check before merging process. Supports in all Version of Windows and Outlook. Capable in ANSI and also UNICODE formats.
More Info: https://www.kdetools.com/pst-merge.html