Yep, this really winds me up too.
I'm fully sympathetic to the point of view that if you're going to be on the road for a long time, you don't want to be stuck behind anything that impacts your progress in even the slightest way, that means that I do understand why, if done correctly and cooperatively, truckers can be forgiven for wishing to overtake each other; and it also means that when they're getting it exactly wrong, they're holding me up and it makes me mad.
It seems to be a trend that I spend ever more time on the M6, and I get to enjoy the poorer examples of overtaking-lorries all too often. If it's busy surely they could wait, or better yet help each other out, and as is said above, roll off a touch of speed to quicken the manouvere a bit and then both pick it up again. As Andy says, overtaking the guy who's just done you to prove your Scania really is better than his Volvo is particularly boring.
There's a nice trait to the junction near my house which makes for extra HGV related fun too; as you come up the M6 towards J32 signs for the split for the M55 start appearing REALLY early, and invariably HGVs immediately wish to prepare, and instead of waiting for the white line to change move right out to the third lane (of four). That's not too bad in itself, apart from the fact that NOBODY wants to under-take them; even though the HGV driver knows he's out there for the junction and isn't coming back inside, the dopey driver behind probably knows it too, and the rest of us in the massive queue forming behind know it too!
Regards,
Rob.