public static List<T> Clone<T>(this List<T> list) where T : new()
  {
   List<T> items = new List<T>();
   foreach (var m in list)
   {
    var model = new T();
    var ps = model.GetType().GetProperties();
    var properties = m.GetType().GetProperties();
    foreach (var p in properties)
    {
     foreach (var pm in ps)
     {
      if (pm.Name == p.Name)
      {
       pm.SetValue(model, p.GetValue(m));
      }
     }
    }
    items.Add(model);
   }
   return items;
  }

 public static List<T> Clone<T>(this List<T> list) where T : new()
 {
 var str = JsonConvert.SerializeObject(list);
 return JsonConvert.DeserializeObject<List<T>>(str);
 }

public static List<T> Clone<T>(this List<T> list)
  {
   using (Stream objectStream = new MemoryStream())
   {
    IFormatter formatter = new BinaryFormatter();
    formatter.Serialize(objectStream, list);
    objectStream.Seek(0, SeekOrigin.Begin);
    return (List<T>)formatter.Deserialize(objectStream);
   }
  }

private void Test()
{
 List<NormalSetting> list = new List<NormalSetting>();
 list.Add(new NormalSetting { RedisIp = "123" });
 List<NormalSetting> items = list.Clone();
 list[0].RedisIp = "456";
 logMessager.Show("{0}:{1}", list[0].RedisIp, items[0].RedisIp);
}