Duplicate events displayed where single event expected

I’m having a problem with duplicate events displayed where single events are expected when I click the previous 30 days in a 30 day timeline view. I can confirm that when the Data() method is called, I make a call to the database and it returns a list of reservations, and it is returning:

return Content(new SchedulerAjaxData(reservations).Render());

Any thoughts on how to handle this problem?