Wow, yikes, I take multiple Acelas and Regional BC's a week and have for a while now. This has never happened to me since the original change described in this thread occurred... I wonder why that happened to you and so many times? I've only seen one drama where two people had the same seat but it was too far ahead of me to learn what the reason was or how it was resolved. Usually it's just that someone is sitting in the wrong seat.