I cannot say about the other controls, but this ListBox was added a couple of years ago while we were porting RadScheduler for WPF to Silverlight. Since the Silverlight ListBox has certain limitations, we created a dummy control and inherited it in RadScheduler. This ListBox was never intended for public use, hence it does not have control template and is not documented.
I can check about the other duplicate controls that you mentioned if you list them here.
the Telerik team