--- a/pkg/imports/isr.go	Sat Jul 10 01:09:57 2021 +0200
+++ b/pkg/imports/isr.go	Sun Jul 11 13:08:49 2021 +0200
@@ -148,6 +148,7 @@
 	if err != nil {
 		return nil, err
 	}
+	heights = heights.Dedup()
 
 	bns, err := fetchBottleneckResults(ctx, conn)
 	if err != nil {
@@ -246,15 +247,7 @@
 			}
 
 			// Re-classify points.
-			classes := heights.Classify(points.All())
-
-			// Should not happen ... Z values over the top.
-			if n := len(classes) - 1; n > 1 && len(classes[n]) > 0 {
-				// Place the over the top values to the class below.
-				classes[n-1] = append(classes[n-1], classes[n]...)
-				classes[n] = nil
-				classes = classes[:n]
-			}
+			classes := heights.Classify(points)
 
 			// Re-insert points
 			for i, class := range classes {