diff --git a/packages/common/src/services/__tests__/utilities.spec.ts b/packages/common/src/services/__tests__/utilities.spec.ts
index 897e2ac2f..2ebab835a 100644
--- a/packages/common/src/services/__tests__/utilities.spec.ts
+++ b/packages/common/src/services/__tests__/utilities.spec.ts
@@ -57,6 +57,34 @@ describe('Service/Utilies', () => {
       ]);
     });
 
+    it('should produce same result when calling the function twice with input that have a parent/child array and return a hierarchical array structure', () => {
+      const input = [
+        { id: 18, size: 90, dateModified: '2015-03-03', file: 'something.txt', parentId: null, },
+        { id: 11, file: 'Music', parentId: null, },
+        { id: 12, file: 'mp3', parentId: 11, },
+        { id: 16, file: 'rock', parentId: 12, },
+        { id: 17, dateModified: '2015-05-13', file: 'soft.mp3', size: 98, parentId: 16, },
+        { id: 14, file: 'pop', parentId: 12, },
+        { id: 15, dateModified: '2015-03-01', file: 'theme.mp3', size: 85, parentId: 14, },
+      ];
+
+      const output1 = unflattenParentChildArrayToTree(input, { parentPropName: 'parentId', childrenPropName: 'files' });
+      const output2 = unflattenParentChildArrayToTree(input, { parentPropName: 'parentId', childrenPropName: 'files' });
+
+      expect(output1).toEqual([
+        {
+          id: 11, __treeLevel: 0, __collapsed: false, parentId: null, file: 'Music', files: [{
+            id: 12, __treeLevel: 1, __collapsed: false, parentId: 11, file: 'mp3', files: [
+              { id: 14, __treeLevel: 2, __collapsed: false, parentId: 12, file: 'pop', files: [{ id: 15, __treeLevel: 3, parentId: 14, file: 'theme.mp3', dateModified: '2015-03-01', size: 85, }] },
+              { id: 16, __treeLevel: 2, __collapsed: false, parentId: 12, file: 'rock', files: [{ id: 17, __treeLevel: 3, parentId: 16, file: 'soft.mp3', dateModified: '2015-05-13', size: 98, }] },
+            ]
+          }]
+        },
+        { id: 18, __treeLevel: 0, parentId: null, file: 'something.txt', dateModified: '2015-03-03', size: 90, },
+      ]);
+      expect(output1).toEqual(output2);
+    });
+
     it('should take a parent/child array with aggregators and return a hierarchical array structure', () => {
       const input = [
         { id: 18, size: 90, dateModified: '2015-03-03', file: 'something.txt', parentId: null, },
@@ -82,6 +110,34 @@ describe('Service/Utilies', () => {
         { id: 18, __treeLevel: 0, parentId: null, file: 'something.txt', dateModified: '2015-03-03', size: 90, },
       ]);
     });
+
+    it('should produce same result when calling the function twice with input that have a parent/child array with aggregators and return a hierarchical array structure', () => {
+      const input = [
+        { id: 18, size: 90, dateModified: '2015-03-03', file: 'something.txt', parentId: null, },
+        { id: 11, file: 'Music', parentId: null, __treeTotals: { count: { size: 2, }, sum: { size: (98 + 85), }, }, },
+        { id: 12, file: 'mp3', parentId: 11, __treeTotals: { count: { size: 2, }, sum: { size: (98 + 85), }, }, },
+        { id: 16, file: 'rock', parentId: 12, __treeTotals: { count: { size: 2, }, sum: { size: 98, }, }, },
+        { id: 17, dateModified: '2015-05-13', file: 'soft.mp3', size: 98, parentId: 16, },
+        { id: 14, file: 'pop', parentId: 12, __treeTotals: { count: { size: 2, }, sum: { size: 85, }, }, },
+        { id: 15, dateModified: '2015-03-01', file: 'theme.mp3', size: 85, parentId: 14, },
+      ];
+
+      const output1 = unflattenParentChildArrayToTree(input, { aggregators: [new SumAggregator('size')], parentPropName: 'parentId', childrenPropName: 'files' });
+      const output2 = unflattenParentChildArrayToTree(input, { aggregators: [new SumAggregator('size')], parentPropName: 'parentId', childrenPropName: 'files' });
+
+      expect(output1).toEqual([
+        {
+          id: 11, __treeLevel: 0, __collapsed: false, parentId: null, file: 'Music', __treeTotals: { count: { size: 2, }, sum: { size: (98 + 85), }, }, files: [{
+            id: 12, __treeLevel: 1, __collapsed: false, parentId: 11, file: 'mp3', __treeTotals: { count: { size: 2, }, sum: { size: (98 + 85), }, }, files: [
+              { id: 14, __treeLevel: 2, __collapsed: false, parentId: 12, file: 'pop', __treeTotals: { count: { size: 1, }, sum: { size: 85, }, }, files: [{ id: 15, __treeLevel: 3, parentId: 14, file: 'theme.mp3', dateModified: '2015-03-01', size: 85, }] },
+              { id: 16, __treeLevel: 2, __collapsed: false, parentId: 12, file: 'rock', __treeTotals: { count: { size: 1, }, sum: { size: 98, }, }, files: [{ id: 17, __treeLevel: 3, parentId: 16, file: 'soft.mp3', dateModified: '2015-05-13', size: 98, }] },
+            ]
+          }]
+        },
+        { id: 18, __treeLevel: 0, parentId: null, file: 'something.txt', dateModified: '2015-03-03', size: 90, },
+      ]);
+      expect(output1).toEqual(output2);
+    });
   });
 
   describe('cancellablePromise method', () => {
diff --git a/packages/common/src/services/utilities.ts b/packages/common/src/services/utilities.ts
index e1d47a7cc..fbc17a928 100644
--- a/packages/common/src/services/utilities.ts
+++ b/packages/common/src/services/utilities.ts
@@ -123,7 +123,7 @@ export function flattenToParentChildArray<T>(treeArray: T[], options?: { aggrega
   type FlatParentChildArray = Omit<T, keyof typeof childrenPropName>;
 
   if (options?.shouldAddTreeLevelNumber) {
-    if (options?.aggregators) {
+    if (Array.isArray(options?.aggregators)) {
       options.aggregators.forEach((aggregator) => {
         addTreeLevelAndAggregatorsByMutation(treeArray, { childrenPropName, levelPropName, aggregator });
       });
@@ -179,7 +179,13 @@ export function unflattenParentChildArrayToTree<P, T extends P & { [childrenProp
       if (!(childrenPropName in p)) {
         p[childrenPropName] = [];
       }
-      p[childrenPropName].push(item);
+      const existIdx = p[childrenPropName]?.findIndex((x: any) => x.id === item.id);
+      if (existIdx < 0) {
+        p[childrenPropName].push(item);
+      } else {
+        // replace existing one when already exists (probably equal to the same item in the end)
+        p[childrenPropName][existIdx] = item;
+      }
       if (p[collapsedPropName] === undefined) {
         p[collapsedPropName] = options?.initiallyCollapsed ?? false;
       }
@@ -189,7 +195,7 @@ export function unflattenParentChildArrayToTree<P, T extends P & { [childrenProp
   // we need and want the Tree Level,
   // we can do that after the tree is created and mutate the array by adding a __treeLevel property on each item
   // perhaps there might be a way to add this while creating the tree for now that is the easiest way I found
-  if (options?.aggregators) {
+  if (Array.isArray(options?.aggregators)) {
     options.aggregators.forEach((aggregator) => {
       addTreeLevelAndAggregatorsByMutation(roots, { childrenPropName, levelPropName, aggregator }, 0);
     });