Turns out that the 2nd event is getting wired up when jquery creates the dialog. So this is likely a jquery issue. However, if anyone has any ideas for fixing this one please let me know.

Yes, I am seeing the same behavior you've described with effects when using jQuery's UI Dialog. Even without effects on the dialog I get the 2nd call to new Calendar(...), and thus multiple event wrappers created for each rich:calendar icon.

I've solved this issue for the time being with a small hack. Using jQuery I remove the javascript for the calendar component before I create the jQuery dialog. This appears to work and thus far doesn't have any negative effects on the functionality of the rich calendar. As I'm removing in the jQuery on page ready method the rich:calendar javascript has already been called.

            // Before we create the dialog remove the javascript for the rich:calendar control. Avoids duplicate Calendar
            // objects and duplicate events which break the calendar.
            $j('[id$=DateScript]').remove();