no you're absolutely spot on, there are some sublte differences, especially that one on the far right (of pic)
Often it's because a person asks for their head to be a certain way (look more moody, make him look like he's been crying, make him look totally normal etc) and often when I'm painting them i'll make each one ever so slightly different on purpose.... call it artist freedom, or creativity.... so I'm not making each one a carbon copy, but rather each person's head will be slightly different in some way. Usually only noticeable if I pointed it out
to me this makes the idea of having a customised figure more what it should be....a figure that nobody else has. Also, it stops me getting bored painting so many heads.... I can do something different on each one (maybe the strength of the worn out look under his eyes, or maybe the pattern of highlights on his hair.... things like that) but so for each person receiving their one head by itself.... when they look at it, it's still 'Anakin from the film'. you only see the differences when they're all in a line
I don't want to be a factory production line in china
in the case of the one on the far right, the person wanted him to have a more troubled look... like he had sore eyes
(also the paint effects on all of those heads stands out more than it does to the naked eye, as the pics were taken late at night... in the dark with a flash. so the colours are seperated a little more then they are when on the figure and you're looking at it normally)