diff --git a/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts b/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
index f09d936385c..0a413ca9a13 100644
--- a/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
+++ b/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
@@ -164,10 +164,10 @@ export class NotebookContribution implements IWorkbenchContribution {
 		}
 
 		if (id === undefined) {
-			const existingEditors = group.editors.filter(editor => editor.resource && isEqual(editor.resource, resource));
+			const existingEditors = group.editors.filter(editor => editor.resource && isEqual(editor.resource, resource) && !(editor instanceof NotebookEditorInput));
 
 			if (existingEditors.length) {
-				return;
+				return undefined;
 			}
 
 			const userAssociatedEditors = this.getUserAssociatedEditors(resource);