The mystery station is gone now from WU. Since I have three stations on the same pole, I had to enter the locations (long, lat) slightly different so they would show up on the wundermap. It might be that the locations being different that what's in cwop/madis was causing the extra station to show up. However, I've had the setup for several years now, so it's odd that it just showed up. But, anyway, I sent them a trouble report and it's fixed.