"Because more than one output of the same type is unsupported" error when shooting a video

 var myDevice: AVCaptureDevice?
        let devices = AVCaptureDevice.devices()

        for device in devices {
            if(device.position==AVCaptureDevicePosition.Front){
                myDevice=device as ?AVCaptureDevice
            }
        }

        do{
            let videoInput=try AVCaptureDeviceInput (device:myDevice) as AVCaptureDeviceInput
            self.captureSession.addInput (videoInput)
            let audioInput=try AVCaptureDeviceInput (device:self.audioDevice) as AVCaptureDeviceInput
            self.captureSession.addInput(audioInput);
        } catch{

        }

        let movieFileOutput=AVCaptureMovieFileOutput()
        self.captureSession.addOutput(movieFileOutput)
        var videoConnection: AVCaptureConnection?=nil

        for connection: AVCaptureConnection in movieFileOutput.connections as![AVCaptureConnection]{
            print(connection)

            for inputport in connection.inputPorts {
                iflet port = inputport as ?AVCaptureInputPort{
                    print(port)

                    if port.mediaType==AVMediaTypeVideo{
                        videoConnection=connection
                    }
                }

            }
        }

        if((videoConnection?.supportVideoOrientation)!=nil){
            videoConnection?.videoOrientation=AVCaptureVideoOrientation.LandscapeLeft
        }

        self.captureSession.commitConfiguration()
        self.captureSession.addOutput(self.fileOutput)
        self.captureSession.startRunning()