CLR requires a method definition
object Clone() which is not type safe. It is common practice to override this behavior and define a type safe method that returns a copy of the containing class.
It is up to the author to decide if cloning means only shallow copy, or deep copy. For immutable structures containing references it is recommended to do a deep copy. For classes being references themselves it is probably fine to implement a shallow copy.
C# an interface method can be implemented privately with the syntax shown above.