I am not sure for record simultaneously, You need to explore camerawesome package.

Detailed Documentation:
https://docs.page/Apparence-io/camera_awesome/getting_started/multicam

Code Snippet:

CameraAwesomeBuilder.awesome(
    sensorConfig: SensorConfig.multiple(
        sensors: [
            Sensor.position(SensorPosition.back),
            Sensor.position(SensorPosition.front),
        ],
        flashMode: FlashMode.auto,
        aspectRatio: CameraAspectRatios.ratio_16_9,
    ),
    // Other params
)

Expected Result:

Related link for How to use Concurrent cameras:
https://pub.dev/packages/camerawesome#--concurrent-cameras