The best way to merge duplicate Outlook contacts is to use the PST Merger Tool. The software allows users to merge the PST files with emails, contacts, calendars, etc. It supports both ANSI and UNICODE file types of Outlook PST. Moreover, the tool merges multiple PST files into one while maintaining data integrity. You can download the free demo version of the tool, which allows you to merge 25 items.
Know more: https://www.msoutlookhelp.com/pst-merge/

If you're having trouble merging several PST files from Outlook. Use the Softaken Merge PST tool for this. Outlook Archives can be combined into a single PST like- Emails, Contacts, Calendars, etc. As a result, you can merge the chosen folder from several PST files for Outlook. Any user can utilize this program flawlessly because it includes such easy instructions. Additionally, a sample version of this program is available for testing out how it functions.
This application, however, is a standalone software that formerly operated independently of Microsoft Outlook.

Read More:- https://www.softaken.com/guide/combine-join-merge-unite-microsoft-outlook-pst-files/

I advise using the best OSTtoPSTAPP PST Merge Tool, which successfully merges several PSTs into a single.pst file. You can integrate all of the PST file's contents, including emails, contacts, calendars, tasks, journals, and notes, with this program. Additionally, the utility is quite compatible with any Windows version. Additionally, the PST Merge Tool combines Outlook PST files into either a brand-new or pre-existing PST file. Some users don't need to install additional software in order to combine PST files. To learn more about this app's features and capabilities, use the free sample version.
Read More: https://www.osttopstapp.com/pst-merge.html

If you're looking for a way to merge PST data or multiple contacts within Outlook, then you can read the article with a step-by-step guide on how to merge duplicate contact in Outlook.
In addition, the PST Merge Tool allows you to combine various MS Outlook personal folder data files into one PST file. It can merge all the elements of the PST file, including calendars, contacts and emails tasks, and many other things. The tool for merging has several advanced features that operate with the most advanced technology.
Learn More: https://www.techietruck.com/merge-duplicate-contacts-in-outlook/

You can try out **Magus PST merging tool** (https://www.magustools.com/pst-conversion/merge.php) to combine multiple PST files of any Outlook version into one keeping the meta properties intact. You can check the tool and give a try to know the process and working.