I've been passed on the left in similar situations. I guess I've either been lucky or just adequately attentive since none of these incidents has ever caught me unawares. When it happens, I just wait it out and then make my turn. I've only had two cars pass in a row on a couple of occasions. Those are a bit more problematic since they usually involve folks who are engaged in some sort of playful racing.

We really should have some sort of testing and licensing for motorists, don't you think?