Single annotation exists in multiple clusters? about clusterkit HOT 5 OPEN

- (NSMutableOrderedSet<id<MKAnnotation>> *) orderedSet;

- (NSMutableOrderedSet<id<MKAnnotation>> *) orderedSet {
    return _annotations;
}

- (void)updateMapRect:(MKMapRect)visibleMapRect animated:(BOOL)animated {
    if (!self.tree || MKMapRectIsNull(visibleMapRect) || MKMapRectIsEmpty(visibleMapRect)) {
        return;
    }
    
    MKMapRect clusterMapRect = MKMapRectWorld;
    if (self.marginFactor != kCKMarginFactorWorld) {
        clusterMapRect = MKMapRectInset(visibleMapRect,
                                        -self.marginFactor * visibleMapRect.size.width,
                                        -self.marginFactor * visibleMapRect.size.height);
    }
    
    double zoom = self.map.zoom;
    CKClusterAlgorithm *algorithm = (zoom < self.maxZoomLevel)? self.algorithm : [CKClusterAlgorithm new];
    NSArray *clusters = [algorithm clustersInRect:clusterMapRect zoom:zoom tree:self.tree];
    
   //------HERE the moment that delete all duplicates from clusters 
    for (CKCluster* cluster in clusters) {
        for (CKCluster* secondCluster in clusters) {
            
            if (![secondCluster isEqualToCluster:cluster] && [secondCluster intersectsCluster:cluster]) {
                
                NSMutableSet<id<MKAnnotation>> *secondSet = secondCluster.orderedSet.set.mutableCopy;
                
                [cluster.orderedSet minusSet:secondSet];
            }
        }
    }
    //---------------------------------------
    NSMutableSet *newClusters = [NSMutableSet setWithArray:clusters];
    NSMutableSet *oldClusters = [NSMutableSet setWithSet:_clusters];
    
    [oldClusters minusSet:newClusters];
    [newClusters minusSet:_clusters];
    
    if (visibleMapRect.size.width > _visibleMapRect.size.width) {
        [self collapse:oldClusters.allObjects to:newClusters.allObjects in:visibleMapRect];
        
    } else if (visibleMapRect.size.width < _visibleMapRect.size.width) {
        [self expand:newClusters.allObjects from:oldClusters.allObjects in:visibleMapRect];
        
    } else {
        [self.map addClusters:newClusters.allObjects];
        [self.map removeClusters:oldClusters.allObjects];
    }
    
    [_clusters minusSet:oldClusters];
    [_clusters unionSet:newClusters];
    
    _visibleMapRect = visibleMapRect;
}