Event called twice! WHY?

Hello, I have a Problem with Events. They are calling twice!
(This code in Room script)
In Awake I do event callback :
PhotonNetwork.OnEventCall += OnEvent;

In Start I send event to Master Client

RaiseEventOptions rs = new RaiseEventOptions();
rs.Receivers = ReceiverGroup.MasterClient;
PhotonNetwork.RaiseEvent(0, 0, true, rs);

In OnEvent I got this by 0 eventCode

if (!PhotonNetwork.isMasterClient)
     return;
//Something code

First time events work right,
but I leave room and disconnect Photon(using this code).
PhotonNetwork.Disconnect();
and then again connect to Server(without restart game) and create room and THIS EVENT CALLING TWICE!! (//Something code run twice!). How to fix?