Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs
===================================================================
diff -u -r31012b85637f7fcf6b28f498fc996edcda2eb505 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 31012b85637f7fcf6b28f498fc996edcda2eb505)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -197,8 +197,8 @@
         {
             ReferenceLine referenceLine = data.Parent.ReferenceLine;
             IEnumerable<FailureMechanismSection> failureMechanismSections = data.WrappedData.Sections;
-            ObservableCollectionWithSourcePath<StochasticSoilModel> stochasticSoilModels = data.WrappedData.StochasticSoilModels;
-            ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> ringtoetsPipingSurfaceLines = data.WrappedData.SurfaceLines;
+            ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel> stochasticSoilModels = data.WrappedData.StochasticSoilModels;
+            ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> ringtoetsPipingSurfaceLines = data.WrappedData.SurfaceLines;
             HydraulicBoundaryDatabase hydraulicBoundaryDatabase = data.Parent.HydraulicBoundaryDatabase;
             IEnumerable<PipingCalculationScenario> calculations =
                 data.WrappedData.CalculationsGroup.GetCalculations().Cast<PipingCalculationScenario>();