Go to Reports > Population Reports > Potential Duplicate Customers.
In the Options section, select one or more of the listed options that you want to compare when searching for matching (duplicate) customer information.
Note: Try disabling Show Customer Alternate Keys? and/or Show Customer Membership Packages? to improve report performance.
To only return customers with a specific membership package, select the Package that you want to search for.
Select the Output Type for the report.
Click Run Report.