[Applies to: Microsoft Dynamics CRM 4.0]
Duplicate detection can take place only if duplicate detection is enabled in Duplicate Detection Settings and if at least one duplicate-detection rule exists for the record type.
Typically, most organizations use duplicate detection in as many scenarios as possible to ensure that records are not duplicated. However, if your system has a large number of records, checking for duplicates can hurt performance.
Users will be prompted automatically before saving or importing potential duplicate records of any record type for which a published duplicate-detection rule exists.
Note: Duplicates cannot be detected when a user merges two records, converts a lead, or saves an activity as completed.
All users of Microsoft Dynamics CRM Online for Outlook must select how they want duplicate detection to work when they synchronize data. By default, duplicates are not detected when Microsoft Dynamics CRM Online for Outlook synchronizes records. More information: Synchronize Data
Each time users define a data import job, the choice of whether to check for duplicates is available. More information: Work with Imports