Yup exactly, definitely do not login from that I.P on your old accounts if you do change it. They have way more problems to worry about, trust me. They don't have professional tracking systems and dedicated staff for it, just a simple system that runs I.Ps like that. Good luck!
Get a new IP and you'll be set. As some have stated before, they've got better things to do. They might track your IP if you're a known RWTer or something of the sort that gets under their skin.