The marker manager specifies a default duplication mode that is used for the markers it creates when the marker is added. The marker manager accepts three values for the defaultDuplicationMode property:

When a marker manager is prompted to create a marker that is identical to one that already exists for a given order or commerce item, the marker manager can discard the new marker (NO_DUPLICATES), replace the original with the duplicate (REPLACE_DUPLICATES),or accept the new marker in addition to the original (ALLOW_DUPLICATES). Fewer markers cause quicker response in queries for a particular marker.

When you specify NO_DUPLICATES or REPLACE_DUPLICATES, the marker manager relies on a compare component to determine whether a new marker is a duplicate of any existing ones. By default, the defaultMarkerDuplicateComparator property is set to /atg/markers/CompareByDefaultProperties, which identifies two markers as identical when they have the same values in their key, value, and data properties. Oracle ATG Web Commerce includes another component, /atg/markers/userprofiling/CompareByKeyAndValue, which determines equality based on the values of only the key and value properties.