using System;

using System.Collections.Generic;

using System.Linq;

​

namespace ConsoleApplication2

{

    public class Program

    {

        public static void Main(string[] args)

        {

            var list = new List<A>

            {

                new A {Code = "C1", Description = "DESC1"}, new A {Code = "c1", Description = "desc1"},

                new A {Code = "C2", Description = "DESC2"}

            };

​

            var distinct = list.Distinct(new CaseInsensitiveComparer());

​

            Console.WriteLine(distinct.Count()); // outputs 2. And you can inspect to see it filters correctly.

        }

    }

​

    public class CaseInsensitiveComparer : IEqualityComparer<A>

    {

        public bool Equals(A x, A y)

        {

            return x.Code.Equals(y.Code, StringComparison.OrdinalIgnoreCase) &&

                   x.Description.Equals(y.Description, StringComparison.OrdinalIgnoreCase);

        }

​

        public int GetHashCode(A obj)

        {

            return obj.Code.ToLowerInvariant().GetHashCode();

        }

    }

​

    public class A

    {

        public string Code { get; set; }

        public string Description { get; set; }

    }

}

​