Outlook--Merging Contacts Without Duplication

Before I learned that I can use categories to organize Outlook contacts, I created multiple contacts folders. How can I merge these contacts into my mail Contacts folder without creating duplicates?

I know of no magic built-in procedure to intelligently consolidate multiple folders into one. I recommend this approach:

You can repeat the process for each of the other folders, using a different category in Step 5 for each one. You can't add the category before moving the items into the main Contacts folder because Outlook doesn't merge categories when it merges other data from duplicate items.

Note that the built-in duplicate checker doesn't work if you're using custom forms. Also, it won't merge the notes from one contact into another. If you use the large blank field at the bottom of the contact, you can open both copies of the contact and copy the notes from one copy to the other.

Learn more from "Linking Outlook Contacts" and "Displaying a Contacts Folder Other Than the Default."