fix: Prevent duplicate documents in collection structure

server/models/Collection.test.ts

@@ -111,6 +111,10 @@ describe("#addDocumentToStructure", () => {
     await collection.addDocumentToStructure(newDocument);
     expect(collection.documentStructure!.length).toBe(1);
     expect(collection.documentStructure![0].id).toBe(id);
+
+    // should not append multiple times
+    await collection.addDocumentToStructure(newDocument);
+    expect(collection.documentStructure!.length).toBe(1);
   });
 
   test("should add with an index", async () => {

server/models/Collection.ts

@@ -647,6 +647,10 @@ class Collection extends ParanoidModel {
       this.documentStructure = [];
     }
 
+    if (this.getDocumentTree(document.id)) {
+      return this;
+    }
+
     // If moving existing document with children, use existing structure
     const documentJson = {
       ...(await document.toNavigationNode(options)),