diff --git a/src/editor/editor.tsx b/src/editor/editor.tsx
index 546ddfad327f62242905e23d1ea6b56a78a91ece..5659d3f1e420185b4454536d01eed3d2f6241e71 100644
--- a/src/editor/editor.tsx
+++ b/src/editor/editor.tsx
@@ -188,7 +188,9 @@ export class Editor extends React.PureComponent<any, stateTypes> {
             return;
         }
 
-        this.selectNodes(selectedNodes.concat(this.state.selectedNodes));
+        this.selectNodes([
+            ...new Set(selectedNodes.concat(this.state.selectedNodes)),
+        ]);
     }
 
     /**