using System;

using System.Collections.Generic;

​

using System.Linq;

​

public class Program

{

    static List<Tuple<string, string>> myList = new List<Tuple<string, string>>()

    {

        Tuple.Create<string, string>("B", "A"),

        Tuple.Create<string, string>("A", "B"), // duplicate

        Tuple.Create<string, string>("C", "B"),

        Tuple.Create<string, string>("C", "B"), // duplicate

        Tuple.Create<string, string>("A", "D"),

        Tuple.Create<string, string>("E", "F"),

        Tuple.Create<string, string>("F", "E"), // duplicate        

    };

​

    public static void Main()

    {

​

        var result =

            from y in 

            from x in myList

            select new { Original = x, SortedPair = new[] { x.Item1, x.Item2 }.OrderBy(s => s).ToArray() }  

            group y by new { NormalizedTuple = Tuple.Create<string,string>(y.SortedPair[0], y.SortedPair[1]) } into grp

            select new { Pair = grp.Key.NormalizedTuple, Original = grp.First().Original };

​

​

        foreach(var item in result)

        {

            Console.WriteLine("Pair: {0} {1}", item.Original.Item1, item.Original.Item2);

        }

    }

}