Applies to Dynamics 365 (online), version 9.x

Duplicate records can creep into your data when you or others enter data manually or import data in bulk. Dynamics 365 helps you address potential duplicates by providing duplicate detection for accounts, contacts, and leads. Your administrator may also set up duplicate detection rules for other situations.

For example, let's say you enter a contact record, Jim Glynn, along with a mobile phone number. The duplicate detection rule discovers that you already have a similar record, and displays this dialog box.

Duplicate contact record detectied in Dynamics 365

You're not sure if this is a new record (one that happens to have the same name as an existing contact) or a duplicate, so you click Save.

Next, you go to the My Active Contacts list and see that now you have two records with the same name. After reviewing the records, you determine that they're duplicates that need to be merged.

Duplicate contacts listed in the My Active Contacts list in Dynamics 365

Dynamics 365 includes duplicate detection rules for accounts, contacts, and leads. These rules are automatically turned on, so you don’t have to do anything to set up duplicate detection for these record types.


If available on your system, you may also be able to check for duplicates of other record types, in addition to contacts, accounts, and leads. Check with your system administrator. Find your Dynamics 365 administrator or support person

Merge duplicate records

  1. Select the duplicate records, and then click Merge.

    Merge records button in Dynamics 365

  2. In the Merge Records dialog box, select the master record (the one you want to keep), and then select any fields in the new record that you want to merge into the master record. Data in these fields may override the existing data in the master record. Click OK.

    Dialog box for merging records in Dynamics 365


There are three situations when duplicates may be found:

  • When a record is created or updated.

    • When you're using Dynamics 365 for Outlook and you go from offline to online.
    • When you import data using the Import Data wizard.

    Duplicates aren't detected when you merge records, convert a lead, save an activity as completed, or change the status of a record, such as activating or reactivating a record.

For system administrators

If you are a system administrator responsible for setting up and managing duplicate detection, see the following topics: