Can I apply to both Oxford and Cambridge for my PGCE?

I know that for an undergraduate degree, you're only allowed to apply for one institution, but have been told that for post-graduate study this rule does not apply. Is this true and does it count for a PGCE? As you opt for four universities and the application is only passed from one to the next if not accepted, I was wondering whether it be one or the other.

I'm in the early stages of applying and can't find a lot of information online.