Dual left turn lanes increase the left turn flow for busy roads, however also increases the chance of people doing unpredictable things.
This isn’t the first time I’ve captured issues with dual left turn lanes. Last year I also captured someone cutting me off from the inside to outside lane at the same intersection. (coincidentally they are both dark coloured Range Rovers. Hmm.)
When making a dual left turn lane, especially if you are the first person in line, please follow the guiding lane markers. And as a general learning point, always be aware of the other drivers around you in the dual lane in case they make erratic movements or lane changes.