using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var m1 = new MyEntity() { Id = 1, Name = "1x" };

        var m2 = new MyEntity() { Id = 1, Name = "1y" };

        var m3 = new MyEntity() { Id = 3, Name = "3" };

        var m4 = new MyEntity() { Id = 4, Name = "4" };

        var list = new List<MyEntity>() { m1, m2, m3, m4 };

        foreach(var l in list) {

            Console.WriteLine(l.Name);

        }

        var list2 = list.DistinctBy(x => x.Id);

        foreach(var ll in list2) {

            Console.WriteLine(ll.Name);

        }

    }

}

​

public class MyEntity {

    public int Id {get; set;}

    public string Name {get; set;}

}

​