Oxford Skype Interviews and Pooling.

I'm applying to Oxford for the History and Politics course. Are international students conducting interviews over skype ever offered more than one interview? I realise that the pooling at Oxford takes place while the one on one interviews are going on at campus. But since Skype interviews are generally held before the ones on campus (that's what I've heard), how likely is it for deserving skype candidates, who cannot be accommodated in the college they applied to for any reason, to get an interview at another college? Should this affect my choice of college? Should I apply to less-subscribed college for better chances if I won't get at least two interviews, because it's impossible for me to arrange a visa in less than a week.