diff --git a/frontend/src/core/cells/__tests__/add-missing-import.test.ts b/frontend/src/core/cells/__tests__/add-missing-import.test.ts
index 80f330e6b0e..d85028ce48a 100644
--- a/frontend/src/core/cells/__tests__/add-missing-import.test.ts
+++ b/frontend/src/core/cells/__tests__/add-missing-import.test.ts
@@ -1,18 +1,35 @@
 /* Copyright 2024 Marimo. All rights reserved. */
 
 import { createStore } from "jotai";
-import { describe, expect, it, vi } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { MockNotebook } from "@/__mocks__/notebook";
+import { MockRequestClient } from "@/__mocks__/requests";
+import { store } from "@/core/state/jotai";
 import { variablesAtom } from "@/core/variables/state";
 import type { Variables } from "@/core/variables/types";
-import { CollapsibleTree, MultiColumn } from "@/utils/id-tree";
-import { maybeAddMissingImport } from "../add-missing-import";
-import { type NotebookState, notebookAtom } from "../cells";
+import {
+  maybeAddAltairImport,
+  maybeAddMarimoImport,
+  maybeAddMissingImport,
+} from "../add-missing-import";
+import { notebookAtom } from "../cells";
 import type { CellId } from "../ids";
-import type { CellData } from "../types";
 
-const CELL_IDS = new MultiColumn([CollapsibleTree.from(["1" as CellId])]);
+// Mock the getRequestClient function
+const mockRequestClient = MockRequestClient.create();
+vi.mock("@/core/network/requests", () => ({
+  getRequestClient: () => mockRequestClient,
+}));
+
+const Cell1 = "1" as CellId;
+const Cell2 = "2" as CellId;
 
 describe("maybeAddMissingImport", () => {
+  beforeEach(() => {
+    store.set(variablesAtom, {} as Variables);
+    store.set(notebookAtom, MockNotebook.notebookState({ cellData: {} }));
+  });
+
   it("should not add an import if the variable is already in the variables state", () => {
     const appStore = createStore();
     appStore.set(variablesAtom, { mo: {} } as Variables);
@@ -36,14 +53,14 @@ describe("maybeAddMissingImport", () => {
     (code) => {
       const appStore = createStore();
       appStore.set(variablesAtom, {} as Variables);
-      appStore.set(notebookAtom, {
-        cellData: {
-          ["1" as CellId]: {
-            code: code,
-          } as CellData,
-        },
-        cellIds: CELL_IDS,
-      } as NotebookState);
+      appStore.set(
+        notebookAtom,
+        MockNotebook.notebookState({
+          cellData: {
+            [Cell1]: { code: code },
+          },
+        }),
+      );
       const onAddImport = vi.fn();
       maybeAddMissingImport({
         moduleName: "marimo",
@@ -58,14 +75,14 @@ describe("maybeAddMissingImport", () => {
   it("should add an import if the variable is not in the variables state and the import statement does not exist in the notebook", () => {
     const appStore = createStore();
     appStore.set(variablesAtom, {} as Variables);
-    appStore.set(notebookAtom, {
-      cellData: {
-        ["1" as CellId]: {
-          code: "mo.md('hello')",
-        } as CellData,
-      },
-      cellIds: CELL_IDS,
-    } as NotebookState);
+    appStore.set(
+      notebookAtom,
+      MockNotebook.notebookState({
+        cellData: {
+          [Cell1]: { code: "mo.md('hello')" },
+        },
+      }),
+    );
     const onAddImport = vi.fn();
     maybeAddMissingImport({
       moduleName: "marimo",
@@ -75,4 +92,32 @@ describe("maybeAddMissingImport", () => {
     });
     expect(onAddImport).toHaveBeenCalledWith("import marimo as mo");
   });
+
+  it("should not create a new cell if import already exists due to skipIfCodeExists", () => {
+    const addImports = [maybeAddMarimoImport, maybeAddAltairImport];
+    for (const addImport of addImports) {
+      store.set(variablesAtom, {} as Variables);
+      store.set(
+        notebookAtom,
+        MockNotebook.notebookState({
+          cellData: {
+            [Cell1]: { code: "import marimo as mo" },
+            [Cell2]: { code: "import altair as alt" },
+          },
+        }),
+      );
+
+      const createNewCell = vi.fn();
+      const result = addImport({
+        autoInstantiate: false,
+        createNewCell,
+        fromCellId: Cell1,
+        before: false,
+      });
+
+      // Should not create a new cell since the import already exists
+      expect(createNewCell).not.toHaveBeenCalled();
+      expect(result).toBeNull();
+    }
+  });
 });
diff --git a/frontend/src/core/cells/add-missing-import.ts b/frontend/src/core/cells/add-missing-import.ts
index e1a2e2d5955..dbaa638523a 100644
--- a/frontend/src/core/cells/add-missing-import.ts
+++ b/frontend/src/core/cells/add-missing-import.ts
@@ -80,6 +80,7 @@ export function maybeAddMarimoImport({
         code: importStatement,
         lastCodeRun: autoInstantiate ? importStatement : undefined,
         newCellId: newCellId,
+        skipIfCodeExists: true,
         autoFocus: false,
       });
       if (autoInstantiate) {
@@ -101,19 +102,21 @@ export function maybeAddAltairImport({
   autoInstantiate: boolean;
   createNewCell: CellActions["createNewCell"];
   fromCellId?: CellId | null;
-}): boolean {
+}): CellId | null {
   const client = getRequestClient();
-  return maybeAddMissingImport({
+  let newCellId: CellId | null = null;
+  const added = maybeAddMissingImport({
     moduleName: "altair",
     variableName: "alt",
     onAddImport: (importStatement) => {
-      const newCellId = CellId.create();
+      newCellId = CellId.create();
       createNewCell({
         cellId: fromCellId ?? "__end__",
         before: false,
         code: importStatement,
         lastCodeRun: autoInstantiate ? importStatement : undefined,
         newCellId: newCellId,
+        skipIfCodeExists: true,
         autoFocus: false,
       });
       if (autoInstantiate) {
@@ -124,4 +127,5 @@ export function maybeAddAltairImport({
       }
     },
   });
+  return added ? newCellId : null;
 }