frankly, i think they saw you, but i think a lot of car drivers have got into the habit of treating both lanes seperately.
they move out into the first lane and make the assumption traffic will just stop because theyre in front of you.. they then seperately move into the 2nd lane..
essentially, what you might do if the traffic was horrendous but instead they just do it all the time..
however, they don't change this behaviour with a cyclist, because they have no concept that
1.your brakes arent as good as a car driver
2. frankly it takes a lot of effort keeping up 20, so i dont want to brake just because you want to save 10 seconds at a junction.
in my car i think this is poor driving, they know they're pulling out in front of you, but assume you will/can stop in time, but when cycling it's appalling..