clonable

void Main()
{
    var class1 = new MyClass { Data = "class1" };
    var list1 = new List<MyClass> { class1 };
    var list2 = list1.CloneListAndContent();

    list2.First().Data = "class2";

    list1.First().Data.Dump();
    list2.First().Data.Dump();

}

public static class MyExtensions
{
    public static List<T> CloneListAndContent<T>(this List<T> list) where T : class
    {
        var clonedList = new List<T>();
        foreach (var element in list)
            clonedList.Add((T)((ICloneable)element).Clone());
        return clonedList;
    }
}

public class MyClass : ICloneable
{
    public string Data { get; set; }

    public object Clone()
    {
        return new MyClass
        {
            Data = this.Data
        };
    }
}