title: React full calendar dragging save to state
body: <p>Hello i use dragging in full calendar and i save events in a state but it duplicates the event in frontend, see example here: <a href="https://codesandbox.io/s/fullcalendar-dragging-6js74" rel="nofollow noreferrer">https://codesandbox.io/s/fullcalendar-dragging-6js74</a></p>
  
  <p>how can i store the event in the state without duplicating,</p>
  
  <p>i think it shows one from the state and one from the calendar it self but i need to show only state one because i also store events added on click and on select in the same state.</p>
  
  <p>any solutions please?</p>