diff --git a/packages/super-editor/src/core/Editor.ts b/packages/super-editor/src/core/Editor.ts
index 9ff9b0b917..5122123b58 100644
--- a/packages/super-editor/src/core/Editor.ts
+++ b/packages/super-editor/src/core/Editor.ts
@@ -34,7 +34,7 @@ import {
 import { AnnotatorHelpers } from '@helpers/annotator.js';
 import { prepareCommentsForExport, prepareCommentsForImport } from '@extensions/comment/comments-helpers.js';
 import DocxZipper from '@core/DocxZipper.js';
-import { generateCollaborationData } from '@extensions/collaboration/collaboration.js';
+import { generateCollaborationData, cancelDebouncedDocxUpdate } from '@extensions/collaboration/collaboration.js';
 import { useHighContrastMode } from '../composables/use-high-contrast-mode.js';
 import { updateYdocDocxData } from '@extensions/collaboration/collaboration-helpers.js';
 import { setImageNodeSelection } from './helpers/setImageNodeSelection.js';
@@ -3164,7 +3164,11 @@ export class Editor extends EventEmitter<EditorEventMap> {
     this.initDefaultStyles();
 
     if (this.options.ydoc && this.options.collaborationProvider) {
-      updateYdocDocxData(this, this.options.ydoc);
+      // Cancel any pending debounced docx update — we are about to do a
+      // fresh export with the new file data. Without cancel, the debounced
+      // export from the previous transaction cycle could fire redundantly.
+      cancelDebouncedDocxUpdate(this);
+      await updateYdocDocxData(this, this.options.ydoc);
       this.initializeCollaborationData();
     } else {
       this.#insertNewFileData();
diff --git a/packages/super-editor/src/extensions/collaboration/collaboration-helpers.js b/packages/super-editor/src/extensions/collaboration/collaboration-helpers.js
index e145f9eb41..9494e490a8 100644
--- a/packages/super-editor/src/extensions/collaboration/collaboration-helpers.js
+++ b/packages/super-editor/src/extensions/collaboration/collaboration-helpers.js
@@ -1,15 +1,50 @@
+// In-flight deduplication: if an export is already running for this (editor, ydoc)
+// pair, subsequent calls return the same promise instead of spawning a parallel export.
+// Keyed as editor → WeakMap<ydoc, promise> so that calls targeting different ydoc
+// instances (e.g. generateCollaborationData's temp ydoc vs editor.options.ydoc) each
+// get their own export run.
+const inFlightUpdates = new WeakMap();
+
 /**
  * Update the Ydoc document data with the latest Docx XML.
  *
+ * Deduplicates concurrent calls for the same (editor, ydoc) pair — if an
+ * export is already in progress for that exact target, the existing promise is
+ * returned instead of starting a second expensive exportDocx() call.
+ *
  * @param {Editor} editor The editor instance
+ * @param {import('yjs').Doc} [ydoc] Target ydoc (defaults to editor.options.ydoc)
  * @returns {Promise<void>}
  */
-export const updateYdocDocxData = async (editor, ydoc) => {
-  try {
-    ydoc = ydoc || editor?.options?.ydoc;
-    if (!ydoc || ydoc.isDestroyed) return;
-    if (!editor || editor.isDestroyed) return;
+export const updateYdocDocxData = (editor, ydoc) => {
+  ydoc = ydoc || editor?.options?.ydoc;
+  if (!ydoc || ydoc.isDestroyed) return Promise.resolve();
+  if (!editor || editor.isDestroyed) return Promise.resolve();
+
+  let ydocMap = inFlightUpdates.get(editor);
+  if (!ydocMap) {
+    ydocMap = new WeakMap();
+    inFlightUpdates.set(editor, ydocMap);
+  }
+
+  const existing = ydocMap.get(ydoc);
+  if (existing) {
+    return existing;
+  }
 
+  const promise = _doUpdateYdocDocxData(editor, ydoc).finally(() => {
+    const map = inFlightUpdates.get(editor);
+    if (map && map.get(ydoc) === promise) {
+      map.delete(ydoc);
+    }
+  });
+
+  ydocMap.set(ydoc, promise);
+  return promise;
+};
+
+const _doUpdateYdocDocxData = async (editor, ydoc) => {
+  try {
     const metaMap = ydoc.getMap('meta');
     const docxValue = metaMap.get('docx');
 
diff --git a/packages/super-editor/src/extensions/collaboration/collaboration.d.ts b/packages/super-editor/src/extensions/collaboration/collaboration.d.ts
index 529cc0ca39..148304207b 100644
--- a/packages/super-editor/src/extensions/collaboration/collaboration.d.ts
+++ b/packages/super-editor/src/extensions/collaboration/collaboration.d.ts
@@ -1 +1,2 @@
 export function generateCollaborationData(...args: any[]): any;
+export function cancelDebouncedDocxUpdate(editor: any): void;
diff --git a/packages/super-editor/src/extensions/collaboration/collaboration.js b/packages/super-editor/src/extensions/collaboration/collaboration.js
index ce516d07a7..53b12f9912 100644
--- a/packages/super-editor/src/extensions/collaboration/collaboration.js
+++ b/packages/super-editor/src/extensions/collaboration/collaboration.js
@@ -163,6 +163,22 @@ const checkDocxChanged = (transaction) => {
   return false;
 };
 
+// Stores the debounced update cancel function per editor so replaceFile
+// can cancel pending debounced exports after doing its own direct export.
+const debouncedDocxUpdateByEditor = new WeakMap();
+
+/**
+ * Cancel any pending debounced updateYdocDocxData call for the given editor.
+ * Called from replaceFile to prevent stale debounced exports from running
+ * after the direct export has already been done.
+ *
+ * @param {Editor} editor
+ */
+export const cancelDebouncedDocxUpdate = (editor) => {
+  const cancel = debouncedDocxUpdateByEditor.get(editor);
+  if (cancel) cancel();
+};
+
 const initDocumentListener = ({ ydoc, editor }) => {
   // 30s debounce: the actual document content syncs in real-time via
   // y-prosemirror's XmlFragment. This DOCX blob is supplementary data
@@ -178,6 +194,8 @@ const initDocumentListener = ({ ydoc, editor }) => {
     { maxWait: 60000 },
   );
 
+  debouncedDocxUpdateByEditor.set(editor, () => debouncedUpdate.cancel());
+
   const afterTransactionHandler = (transaction) => {
     const { local } = transaction;
 
@@ -193,6 +211,7 @@ const initDocumentListener = ({ ydoc, editor }) => {
   return () => {
     ydoc.off('afterTransaction', afterTransactionHandler);
     debouncedUpdate.cancel();
+    debouncedDocxUpdateByEditor.delete(editor);
   };
 };
 
diff --git a/packages/super-editor/src/extensions/collaboration/collaboration.test.js b/packages/super-editor/src/extensions/collaboration/collaboration.test.js
index 5cd6c3ef14..18ac6101e6 100644
--- a/packages/super-editor/src/extensions/collaboration/collaboration.test.js
+++ b/packages/super-editor/src/extensions/collaboration/collaboration.test.js
@@ -207,6 +207,39 @@ describe('collaboration helpers', () => {
     expect(optionsYdoc._maps.metas.set).not.toHaveBeenCalled();
   });
 
+  it('updates each target ydoc when concurrent calls use the same editor', async () => {
+    const optionsYdoc = createYDocStub();
+    const explicitYdoc = createYDocStub();
+    optionsYdoc._maps.metas.store.set('docx', [{ name: 'word/document.xml', content: '<old options />' }]);
+    explicitYdoc._maps.metas.store.set('docx', [{ name: 'word/document.xml', content: '<old explicit />' }]);
+
+    let resolveFirstExport;
+    const firstExport = new Promise((resolve) => {
+      resolveFirstExport = resolve;
+    });
+
+    const editor = {
+      options: { ydoc: optionsYdoc, user: { id: 'user-concurrent' } },
+      exportDocx: vi
+        .fn()
+        .mockReturnValueOnce(firstExport)
+        .mockResolvedValueOnce({ 'word/document.xml': '<new explicit />' }),
+    };
+
+    const optionsUpdate = updateYdocDocxData(editor);
+    const explicitUpdate = updateYdocDocxData(editor, explicitYdoc);
+
+    resolveFirstExport({ 'word/document.xml': '<new options />' });
+    await Promise.all([optionsUpdate, explicitUpdate]);
+
+    expect(optionsYdoc._maps.metas.set).toHaveBeenCalledWith('docx', [
+      { name: 'word/document.xml', content: '<new options />' },
+    ]);
+    expect(explicitYdoc._maps.metas.set).toHaveBeenCalledWith('docx', [
+      { name: 'word/document.xml', content: '<new explicit />' },
+    ]);
+  });
+
   it('skips transaction when docx content has not changed', async () => {
     const existingDocx = [
       { name: 'word/document.xml', content: '<same />' },