Human vs. Machine

I've heard a lot of talk about the fact that there may be 2 androids in Prometheus, David being one and perhaps Vickers being one as well and hiding her true identity, but I've become convinced that this won't be the case. What really got me thinking about this is the following quote from Charlize Theron I read [url=http://io9.com/5823610/first-footage-from-ridley-scotts-prometheus-made-our-space-helmets-explode]here[/url]. It's really old, I know, but I think how she describes her character is significant: [quote]She's very different from anything I've done. She's a suit, essentially. She's kind of the machine that runs the machine, that takes this mission into space. At first, she comes across like a suit, very cold and frigid, it seems that it's all about the economics for her — she doesn't really come from one side or the other, she's not a scientist or a believer.[/quote] It occurred to me when reading this that having Vickers also be an android would squander a golden opportunity to do something that Ridley was so obsessed with doing in the first film: exploring the lines dividing the human from the mechanical (or artificial), and especially where those lines blur. We already know that Vickers is something of an antagonist, and that David may very well be a crucial protagonist in the story. I speculate then, that David's actions and decisions (when the sh*t hits the proverbial fan) will stand in stark contrast to Vickers' actions in the same scenarios. David, the android, will appear to be the far more sympathetic and "human" character, transcending his artificial nature and making choices that benefit the crew and humanity at large. Vickers, on the other hand, will be the cold, calculating, company tool. She will consider her fellow humans expendable in the service of the company's interests, and may likely end up sacrificing one or more of them to further this end. In this way Ridley will (again) pose to us the question: how do we define ourselves as human? Pure speculation of course, but I hope we get to see something like this in the film.