When you see somebody walking towards you on a narrow path, and you're there walking double-file with your friend.. it should be a natural motion for either you or your friend to move into single-file and allow me to walk past without having to step into moving traffic.
Further more, when you're walking perpendicular to the flow of pedestrians, it would make sense for you to not stop mid-step, because the 'flow' doesn't like having to guess what the hell you're doing.