diff --git a/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php
index 760d50b11..2348f22bf 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php
+++ b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php
@@ -59,7 +59,7 @@ class UniqueConstraint extends BaseConstraint
             if ($containerNode != null && $level == 2) {
                 // collect (additional) key fields
                 $keyFields = array($nodeName);
-                $keyFields = array_merge($keyFields, $this->getOptionValueList('addFields'));
+                $keyFields = array_unique(array_merge($keyFields, $this->getOptionValueList('addFields')));
                 // calculate the key for this node
                 $nodeKey = '';
                 foreach ($keyFields as $field) {