I came back after being gone for nearly a week and came back with something strange appearing at the login of wotlk. I logged on this website and had to go through the 2 step verification (because i my dsl ip changes) anyway after i finally was able to login the authenticator on the wotlk login was still there
You have "Remember Account Name" checked so it also remembers that you have 2 step authentication enabled. But if you use email authentication, it's not going to work this way. Try leaving the field empty and see if it works. If not, unchecking "Remember Account Name" might be the easiest solution.