Windows RegisterDeviceNotificationon，OndeviceChange被调用多次

我正在使用RegisterDeviceNotification在添加设备时获取通知。 我收到的通知是正确的，但是对于任何连接的设备，我都会多次收到OnDeviceChange呼叫（大约5-6次）。 代码如下：

     RegisterNotificaiton()
     {
        DEV_BROADCAST_DEVICEINTERFACE *pDev;
    pDev = new DEV_BROADCAST_DEVICEINTERFACE();
    if(NULL != pDev)
    {
    memset( pDev, 0, sizeof(DEV_BROADCAST_DEVICEINTERFACE) );
    pDev->dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
    pDev->dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;

    pDev->dbcc_classguid = GUID_USB;
    m_hNotifyDevNode = RegisterDeviceNotification( this->GetSafeHwnd(), pDev,                                       DEVICE_NOTIFY_WINDOW_HANDLE | 4);
    if(NULL != pDev)
    {
        delete pDev;
        pDev = NULL;
    }
   }
    }

    BOOL CMainFrame::OnDeviceChange(UINT wParam, DWORD_PTR lParam)
    {
 switch ( wParam )
      {
    case DBT_DEVICEARRIVAL:
    {
       ; // Do something 
    }
    break;
    case DBT_DEVICEREMOVECOMPLETE:
    {
                ; // Do something
    }
           default:
               break;
          }
return true;

     }