I suggest OSTtoPSTApp PST Duplicate Remover, if you want the best utility to delete multiple duplicate PST files without a single error, and you can also remove duplicate OST files by using this application. The utility helps you to remove duplicate PST files without harming your original data. You can delete multiple duplicate PST files in one click, and it keeps your storage space. This is designed with a simple GUI so that it is useful for Technical and non-technical users to use and delete all duplicate PST files without technical skills. Users just need to follow a few steps to simply remove duplicate PST files without installing MS Outlook.