Find the duplicates value in Array in C#

Finding the duplicate value in array using C# code.

class Program

    {

        static void Main(string[] args)

        {

            string InuputString = "Input Array \n";

             Console.WriteLine(InuputString);

             ArrayList obj = new ArrayList(){"1","4","Test","^","1","67","43","4","Ret","78"};

             for (int i = 0; i < obj.Count; i++)

             {

                 Console.Write(obj[i] + " ");

             }

             GetDuplicateArryValue(obj);

        }

        public static void GetDuplicateArryValue(ArrayList arr)

        {

            //to store all the duplicate values in Array list

            ArrayList dup = new ArrayList();

            for (int i = 0; i < arr.Count; i++)

            {

                for (int j = i + 1; j < arr.Count; j++)

                {

                    if (arr[i].Equals(arr[j]))

                    {

                        //When duplicate value is found, check

                        //whether the value not contained in the dup array list

                        if (!dup.Contains(arr[i]))

                        {

                            dup.Add(arr[i]);

                        }

                    }

                }

            }

            Console.WriteLine("\n Duplicates Number Are");

            for (int i = 0; i < dup.Count; i++)

            {

                Console.Write(dup[i] + " ");

            }

            Console.WriteLine();

        }

    }

OUTPUT :