using System;

using System.Collections.Generic;               

public class Program

{

    public static void Main()

    {

        var m = new Dictionary<object, int>();

        var o1 = new object();

        var o2 = o1;

        m[o1] = 1; 

        m[o2] = 2;

        Console.WriteLine(m[o1]);

​

    }

}