The number of Contacts marked as Duplicates should be kept to a minimum.
The Customer Portal Report Card will give an A grade when less than 2% of your active Contacts are flagged as Duplicates (have a "Duplicate of" relationship). Contacts are considered active if they have activity in the Activity Log in the last 365 days.
To view all of your duplicate contacts use the Duplicates View on the Contacts Relationships page, within the People Lists section.
This tool is designed to combine duplicate Contacts into one. All the duplicate Contacts will appear in the drop down of the Tool when launched without a selection. See Combine Contacts Tool for more information.
Ensure to ALWAY search more than one way before adding people to your system
Ensure your church has a "minimum data required" practice. In other words, before someone is added to the system, you must have at least first and last name along with 2 other pieces of information (birthdate, email, phone, address, etc)
If possible, try to collect birthdates as that is one piece of data on an individual that does not change.