Sometimes, duplicate properties are created accidentally. DON'T delete one of the properties to get rid of the duplicate because...

WARNING: Deleting a property will also delete the attached permits, violations, documents, and other data.

In this situation, send us a chat message from the Help menu (see screenshot) with information about the two duplicate properties. We can run a script on the database that will merge the two properties and consolidate all the permits, documents, etc. into the merged property.