public boolean isPossibleDuplicate() {
    return testEventFlag(EventFlags.FLAG_POSSIBLE_DUPLICATE);
  }
If true, the region associated with this event had already applied the operation it
encapsulates when an attempt was made to apply the event.

@return the possibleDuplicate
geode-core/src/main/java/org/apache/geode/internal/cache/EntryEventImpl.java