TIdSocketList - List of duplicated socket handles.

Clone is an overridden TIdSocketList function that implements the method used to create duplicate copies of the socket descriptors stored in the list. 

The return value for the method is a new TIdSocketListDotNet instance created for the cloned socket handles. 

Clone sets the contents of the return value using the Clone method in the ArrayList that implements storage for the list. 

On the .Net platform, the internal ArrayList is updated on return. As A result, the socket list must be copied each time it is accessed in SelectRead and SelectReadList.