Find duplicate records in arraylist

We will know how to Find duplicate records in arraylist. 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections;
namespace Duplicate_Records_in_ArrayList
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            var list = new ArrayList { "Raj", "Raj", "Ravi", "Rahul"};
            var dublicate =
                (from string item in list select item).GroupBy(s => s).Select(
                    group => new { Word = group.Key, Count = group.Count() }).Where(x => x.Count >= 2);

            foreach (var duplicate in dublicate)
            {
                MessageBox.Show("Duplicate records are:" + duplicate.Word);
            }
           
        }
    }
}