Daypilot is calling Pageload multiple times

DayPilot uses the standard ASP.NET CallBack mechanism to communicate with the server side. Each callback fires the respective event handler (e.g. EventMove) but it also goes through Page_Load first. This is how CallBacks work in ASP.NET. You can't prevent Page_Load from firing but you can detect a callback using IsCallBack property:

protected void Page_Load(object sender, EventArgs e)
{
    if (IsCallBack)
    {
      // ... callback detected
    }
}

It's the same approach that you use when detecting PostBacks.