diff --git a/Runtime/Scripts/Core/Cluster.cs b/Runtime/Scripts/Core/Cluster.cs
index 7990031..0a7c2b3 100644
--- a/Runtime/Scripts/Core/Cluster.cs
+++ b/Runtime/Scripts/Core/Cluster.cs
@@ -894,7 +894,10 @@ namespace NanoBrain {
                     foreach (Synapse synapse in neuron.synapses) {
                         if (synapse.neuron.parent.name != cluster.name) {
                             ExternalClusterData clusterData = new(synapse.neuron.parent);
-                            this.clusters.Add(clusterData);
+                            if (this.clusters.Find(data => data.name == clusterData.name) == null) {
+                                this.clusters.Add(clusterData);
+                                //Debug.Log("Add cluster");
+                            }
                         }
                     }
                 }