diff --git a/README.md b/README.md
index 75092f0..4bb2c9d 100644
--- a/README.md
+++ b/README.md
@@ -1017,7 +1017,7 @@ pnpm perf:rbtree
     <td>Counter</td>
   </tr>
   <tr>
-    <td>LinkedHashMap&lt;K, V&gt;</td>
+    <td>ES6 Map&lt;K, V&gt;</td>
     <td>-</td>
     <td>LinkedHashMap&lt;K, V&gt;</td>
     <td>OrderedDict</td>
diff --git a/src/data-structures/binary-tree/binary-tree.ts b/src/data-structures/binary-tree/binary-tree.ts
index 892d434..de27a58 100644
--- a/src/data-structures/binary-tree/binary-tree.ts
+++ b/src/data-structures/binary-tree/binary-tree.ts
@@ -152,9 +152,10 @@ export class BinaryTree<K = any, V = any, R = object, MK = any, MV = any, MR = o
   ) {
     super();
     if (options) {
-      const { iterationType, toEntryFn, isMapMode } = options;
+      const { iterationType, toEntryFn, isMapMode, isDuplicate } = options;
       if (iterationType) this.iterationType = iterationType;
       if (isMapMode !== undefined) this._isMapMode = isMapMode;
+      if (isDuplicate !== undefined) this._isDuplicate = isDuplicate;
       if (typeof toEntryFn === 'function') this._toEntryFn = toEntryFn;
       else if (toEntryFn) throw TypeError('toEntryFn must be a function type');
     }
@@ -170,6 +171,12 @@ export class BinaryTree<K = any, V = any, R = object, MK = any, MV = any, MR = o
     return this._isMapMode;
   }
 
+  protected _isDuplicate = false;
+
+  get isDuplicate() {
+    return this._isDuplicate;
+  }
+
   protected _store = new Map<K, V | undefined>();
 
   get store() {
@@ -356,8 +363,8 @@ export class BinaryTree<K = any, V = any, R = object, MK = any, MV = any, MR = o
    * Space Complexity: O(1)
    *
    * The function `isRange` checks if the input parameter is an instance of the `Range` class.
-   * @param {BTNRep<K, V, BinaryTreeNode<K, V>> | NodePredicate<BinaryTreeNode<K, V>> | Range<K>}
-   * keyNodeEntryOrPredicate - The `keyNodeEntryOrPredicate` parameter in the `isRange` function can be
+   * @param {BTNRep<K, V, BinaryTreeNode<K, V>> | NodePredicate<BinaryTreeNode<K, V>> | Range<K>} keyNodeEntryOrPredicate
+   * - The `keyNodeEntryOrPredicate` parameter in the `isRange` function can be
    * of type `BTNRep<K, V, BinaryTreeNode<K, V>>`, `NodePredicate<BinaryTreeNode<K, V>>`, or
    * `Range<K>`. The function checks if the `keyNodeEntry
    * @returns The `isRange` function is checking if the `keyNodeEntryOrPredicate` parameter is an
@@ -461,11 +468,13 @@ export class BinaryTree<K = any, V = any, R = object, MK = any, MV = any, MR = o
 
       if (!cur) continue;
 
-      // Check for duplicate keys when newNode is not null
-      if (newNode !== null && cur.key === newNode.key) {
-        this._replaceNode(cur, newNode);
-        if (this._isMapMode) this._setValue(cur.key, newValue);
-        return true; // If duplicate keys are found, no insertion is performed
+      if (!this._isDuplicate) {
+        // Check for duplicate keys when newNode is not null
+        if (newNode !== null && cur.key === newNode.key) {
+          this._replaceNode(cur, newNode);
+          if (this._isMapMode) this._setValue(cur.key, newValue);
+          return true; // If duplicate keys are found, no insertion is performed
+        }
       }
 
       // Record the first possible insertion location found
diff --git a/src/types/data-structures/binary-tree/binary-tree.ts b/src/types/data-structures/binary-tree/binary-tree.ts
index 081e9c6..5f632a3 100644
--- a/src/types/data-structures/binary-tree/binary-tree.ts
+++ b/src/types/data-structures/binary-tree/binary-tree.ts
@@ -7,6 +7,7 @@ export type BinaryTreeOptions<K, V, R> = {
   iterationType?: IterationType;
   toEntryFn?: ToEntryFn<K, V, R>;
   isMapMode?: boolean;
+  isDuplicate?: boolean;
 }
 
 export type BinaryTreePrintOptions = { isShowUndefined?: boolean; isShowNull?: boolean; isShowRedBlackNIL?: boolean };
diff --git a/src/types/data-structures/binary-tree/bst.ts b/src/types/data-structures/binary-tree/bst.ts
index dac6932..1b4f741 100644
--- a/src/types/data-structures/binary-tree/bst.ts
+++ b/src/types/data-structures/binary-tree/bst.ts
@@ -2,7 +2,7 @@ import type { BinaryTreeOptions } from './binary-tree';
 import { Comparable } from '../../utils';
 import { OptValue } from '../../common';
 
-export type BSTOptions<K, V, R> = BinaryTreeOptions<K, V, R> & {
+export type BSTOptions<K, V, R> = Omit<BinaryTreeOptions<K, V, R>, 'isDuplicate'> & {
   specifyComparable?: (key: K) => Comparable
   isReverse?: boolean;
 }
diff --git a/test/unit/data-structures/binary-tree/binary-tree.test.ts b/test/unit/data-structures/binary-tree/binary-tree.test.ts
index 382ea30..c1c8d8e 100644
--- a/test/unit/data-structures/binary-tree/binary-tree.test.ts
+++ b/test/unit/data-structures/binary-tree/binary-tree.test.ts
@@ -1434,3 +1434,69 @@ describe('BinaryTree not map mode iterative methods test', () => {
     expect(cloned.get(cloned.root?.right)).toBe('c');
   });
 });
+
+describe('classic use', () => {
+  it('@example determine loan approval using a decision tree', () => {
+    // Decision tree structure
+    const loanDecisionTree = new BinaryTree<string>(
+      ['stableIncome', 'goodCredit', 'Rejected', 'Approved', 'Rejected'],
+      { isDuplicate: true }
+    );
+
+    function determineLoanApproval(
+      node?: BinaryTreeNode<string> | null,
+      conditions?: { [key: string]: boolean }
+    ): string {
+      if (!node) throw new Error('Invalid node');
+
+      // If it's a leaf node, return the decision result
+      if (!node.left && !node.right) return node.key;
+
+      // Check if a valid condition exists for the current node's key
+      return conditions?.[node.key]
+        ? determineLoanApproval(node.left, conditions)
+        : determineLoanApproval(node.right, conditions);
+    }
+
+    // Test case 1: Stable income and good credit score
+    expect(determineLoanApproval(loanDecisionTree.root, { stableIncome: true, goodCredit: true })).toBe('Approved');
+
+    // Test case 2: Stable income but poor credit score
+    expect(determineLoanApproval(loanDecisionTree.root, { stableIncome: true, goodCredit: false })).toBe('Rejected');
+
+    // Test case 3: No stable income
+    expect(determineLoanApproval(loanDecisionTree.root, { stableIncome: false, goodCredit: true })).toBe('Rejected');
+
+    // Test case 4: No stable income and poor credit score
+    expect(determineLoanApproval(loanDecisionTree.root, { stableIncome: false, goodCredit: false })).toBe('Rejected');
+  });
+
+  it('@example evaluate the arithmetic expression represented by the binary tree', () => {
+    const expressionTree = new BinaryTree<number | string>(['+', 3, '*', null, null, 5, '-', null, null, 2, 8]);
+
+    function evaluate(node?: BinaryTreeNode<number | string> | null): number {
+      if (!node) return 0;
+
+      if (typeof node.key === 'number') return node.key;
+
+      const leftValue = evaluate(node.left); // Evaluate the left subtree
+      const rightValue = evaluate(node.right); // Evaluate the right subtree
+
+      // Perform the operation based on the current node's operator
+      switch (node.key) {
+        case '+':
+          return leftValue + rightValue;
+        case '-':
+          return leftValue - rightValue;
+        case '*':
+          return leftValue * rightValue;
+        case '/':
+          return rightValue !== 0 ? leftValue / rightValue : 0; // Handle division by zero
+        default:
+          throw new Error(`Unsupported operator: ${node.key}`);
+      }
+    }
+
+    expect(evaluate(expressionTree.root)).toBe(-27);
+  });
+});