with more search i ended up whit the following solution: Serialize the skeleton to the memory, deserialize to a new object
Here is the code
public static Skeleton Clone(this Skeleton skOrigin)
{
// isso serializa o skeleton para a memoria e recupera novamente, fazendo uma cópia do objeto
MemoryStream ms = new MemoryStream();
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(ms, skOrigin);
ms.Position = 0;
object obj = bf.Deserialize(ms);
ms.Close();
return obj as Skeleton;
}