Is operator working simulation

I think your function is no (theoretical) replacement for the is operator.

1. The is operator takes an object (left) and a type (right) as arguments, not two objects.
2. The is operator considers inheritance. Look at this (executable) example:
C#

using System;

namespace IsOperatorCheck
{
    class Program
    {
        class Sample { }
        class Derived : Sample { }

        static void Main(string[] args)
        {
            Sample s = new Sample();
            Derived d = new Derived();

            Console.WriteLine(s is Sample);
            Console.WriteLine(d is Sample); // !!
            Console.WriteLine(IsOperatorCheck(s, d));

            Console.ReadKey();
        }

        static bool IsOperatorCheck(object arg1, object arg2)
        {
            bool result;
            if (arg1.GetType().IsValueType && arg2.GetType().IsValueType)
                result = (arg1.GetType() == arg2.GetType());
            else
                result = (arg1.GetType().Equals(arg2.GetType()));
            return result;
        }      
    }
}

So maybe you should call your tip: "how to compare object types".