using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

    var fooArray = new List<Foo>()

    {

        new Foo

        {

            valueOne = "Equal Value",

            valueTwo = "Some value"

        },

        new Foo

        {

            valueOne = "Equal Value",

            valueTwo = "Different value"

        },

        new Foo

        {

            valueOne = "Equal Value",

            valueTwo = null

        },

        new Foo

        {

            valueOne = "SomeOtherValue",

            valueTwo = "whatever"

        },

        new Foo

        {

            valueOne = "I have null value, but should still be in list",

            valueTwo = null

        }

    };

    var fooResult = fooArray.Distinct();

    fooResult.Dump();

    }

}

​

​

public class Foo : IEquatable<Foo>

{

    public string valueOne;

    public string valueTwo;

    public int Code { get; set;}

​

    public bool Equals(Foo other)

    {

        if(other == null)

        {

            return false;

        }

        if(this.valueOne == other.valueOne && this.valueTwo == (other.valueTwo ?? this.valueTwo))

        {

            return true;

        }

        return false;

    }

    public override int GetHashCode()

    {

        int hashCode = Code.GetHashCode();

        return hashCode;

    }

}