This article was previously published under Q220837
This article has been archived. It is offered "as is" and will no longer be updated.
NOTE: These procedures only apply if you have installed Outlook with the Internet Mail Only option. To determine your installation type, click About Microsoft Outlook on the Help menu. If you have the Internet Mail Only option installed, you see "Internet Mail Only".
For information about the differences between Microsoft Outlook and Microsoft Outlook Express e-mail clients, click the following article number to view the article in the Microsoft Knowledge Base:
257824 OL2000: Differences Between Outlook and Outlook Express
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
This article describes how to turn off detection of duplicate contacts to allow faster and unattended moving or copying of addresses into the Contacts folder.
Duplicate detection is a new feature of Outlook 2000. This feature addresses the problem of having duplicate entries in a Contact folder. At the time of adding a contact, Outlook checks to see if it is a potential duplicate. If so, you are prompted for a resolution. There are three possible actions that can be taken when prompted. You can update the original contact, add the contact as a duplicate, or do not add the contact.
Duplicate Detection Turned On
Duplicate detection is turned on in the following situations:
When saving a new contact that was manually entered.
When saving a contact originating from an attachment (vCard) or recipient (Add to Contacts).
When copying or moving contacts from one folder to another.
Duplicate Detection Turned Off
Duplicate detection is turned off in the following situations:
Address Importing: When you use the Import Wizard to import contacts from other files or programs.
H/PC Synchronization: When synchronizing items between your desktop computer and your Handheld PC.
When you use the Internet Mail Only version, and set the automatically put people I reply to in Contacts option. To set this option, follow these steps:
On the Tools menu, click Options.
On the Preferences tab, click E-mail options.
Click to select Automatically put people I reply to in.
Click OK twice to close.
The duplicate detection window will also appear if you are adding a person with a security certificate.
Manually Turning Off Duplicate Detection
Turning off duplicate detection can improve performance if you have a large number of contacts to import. This will speed up unattended moving or copying of addresses into the Contacts folder. You may want to turn the feature back on after the import is done.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
The duplicate detection feature can be turned off manually by editing a key in the registry. To edit the registry to turn off duplicate detection, follow these steps:
With the Contact folder selected, on the Edit menu, point to New and click DWORD Value.
Type ConfirmDuplicates, and press ENTER.
Double-click to open the new DWORD Value and in the Edit DWORD Value window type "0" (without quotation marks) to turn off, and "1" (without quotation marks) to turn on duplicate detection.
Exit the registry editor.NOTE: To turn duplicate detection back on use the steps above and in step 7, type 1, to turn on duplicate detection.
For more information about Duplicate Handling, click Microsoft Outlook Help on the Help menu, type Duplicate Detection in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.