By default, Salesforce has three standard duplicate rules for Accounts, Contacts, and Leads. These default rules permit the creation of duplicate records, but they trigger an alert whenever a user attempts to create a duplicate record.

When trying to create a duplicate Contact or Lead from the 'Scanning Queue' you'll be presented with a warning message.

Note: The warning message displayed will depend on your organization's duplicate rule settings.

You can only view or merge a duplicate record in the Scanning Queue if there's at least one duplicate rule configured in 'Scanning Settings.' For better results, it's recommended to choose a distinct field like 'Email' or 'Phone' when setting up the duplicate rule.

After adding a duplicate rule in 'Scanning Settings,' you will receive this message when attempting to create a duplicate record.

You can view the potential duplicate record, merge it with the master record, or create a duplicate.