If a contact has multiple addresses, you can add multiple locations to prevent duplicate contacts. To add multiple addresses to a contact:
Under Records, select Contacts and locate the contact.
After selecting the contact, the address information will display. In the right corner above the address, hover over Manage Locations and select Add Location.
Complete the required address fields and click Save.
To change a location when creating a certificate, after selecting the contact, hover over Actions and select Switch Location. This will allow you to select another location you have saved for the contact.