class Program
    {
        static void Main(string[] args)
        {
            List<Test1> list1 = new List<Test1>(){
                new Test1(1),
                new Test1(2),
                new Test1(3),
                new Test1(4),
                new Test1(5)
            };

            List<Test2> list2 = new List<Test2>(){
                 new Test2(1),
                 new Test2(2),
                 new Test2(3),
                 new Test2(4),
                 new Test2(5)
            };

            foreach (var item in list1) item.Print();

            Console.WriteLine("-------------------------");

            foreach (var item in list2) item.Print();

            Console.ReadKey();
        }
    }

    public class Test1
    {
        public static int Id { get; set; }
        public Test1(int id)
        {
            Id = id;
        }

        public void Print() {
            Console.WriteLine(Id);
        }
    }

    public class Test2 {
        public int Id { get; set; }
        public Test2(int id)
        {
            Id = id;
        }

        public void Print()
        {
            Console.WriteLine(Id);
        }
    }

5
5
5
5
5
-------------------------
1
2
3
4
5