I've checked. High and low bean are supplied by one bulb (HID D2S) and the unit employs a shutter to switch between high and low beam.
You will find it all here
https://www.youtube.com/watch?v=Xy2IWY5JiEg at about 9 mins into the video.
The H7 (halogen) bulb is merely for illumination while turning at low speeds.