using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    private List<SomeDto> Data = new List<SomeDto>();

    private List<SomeDto> OriginalData = new List<SomeDto>();

    public void Main()

    {

        LoadData();

        ChangeData();

        RemoveUnchanged();

        Console.WriteLine("Original list: ");

        foreach(var dto in OriginalData)

        {

            Console.WriteLine(dto.ToString());

        }

        Console.WriteLine("Changed list: ");

        foreach(var dto in Data)

        {

            Console.WriteLine(dto.ToString());

        }

    }

    public void LoadData()

    {

        OriginalData = new List<SomeDto>

        {

            new SomeDto { Id = 1, Code = "T1", Name = "Test1", Description = "First" },

            new SomeDto { Id = 2, Code = "T2", Name = "Test2", Description = "Second" },

            new SomeDto { Id = 3, Code = "T3", Name = "Test3", Description = "Third" },

            new SomeDto { Id = 3, Code = "T4", Name = "Test4", Description = "Forth" }

        };

        Data = OriginalData.Select(x => (SomeDto)x.Clone()).ToList();

    }

    private void ChangeData()

    {

        foreach(var dto in Data)

        {

            if(dto.Id != 2)

            {

                dto.Code = "F" + dto.Id.ToString();

            }

        }

    }

    private void RemoveUnchanged()

    {

        Data.RemoveAll(x => OriginalData.Any(y => y.Equals(x)));

    }

}

public class SomeDto

{

    public int Id { get; set;}

    public string Code { get; set; }

    public string Name { get; set; }

    public string Description { get; set;}

    public object Clone()

        {

            return MemberwiseClone();

        }

    public override string ToString()

    {

        return "Id: " + Id + ", Code: " + Code + ", Name: " + Name + ", Description: " + Description;

    }

    public override bool Equals(object obj)

    {

        return base.Equals(obj);

    }

    public bool Equals(SomeDto obj)

    {

        return obj.Id == Id && obj.Code == Code && obj.Name == Name && obj.Description == Description;

    }

}