public class TestDuplicateDefine : IEqualityComparer<student>

    {

        public bool Equals(student x, student y)

        {

            return x.name == y.name;

        }

        public int GetHashCode(student obj)

        {

            return obj.ToString().GetHashCode();

        }

    }

    public class student

    {

        public string name { get; set; }

        public int id { get; set; }

    }

private void button1_Click(object sender, EventArgs e)

        {

            List<student> list = new List<student>();

            list.Add(new student { name = "", id =  });

            list.Add(new student { name = "", id =  });

            list.Add(new student { name = "", id =  });

            list.Add(new student { name = "", id =  });

            List<student> aa = list.Distinct(new TestDuplicateDefine()).ToList();

        }