There is no such built in functionality in RadScheduler but one possible solution if to get all the information about the appointment in the OnClientFormCreated event save it in a some hidden field's value and then check if it is the same on a click of the button.
One the server side this can be easily made in the AppointmentUpdate event.
Hope this will be helpful.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed