Well, I don't get a lot about Windows 8, but I do about Xbox, and what it seems to me that happened, and since you said that you had never had an Xbox LIVE acount, is that, when you were setting up your PC and put the e-mail, since there was no account associated with it, it just automatically created one.
And, aroud two years earlier, when you created an Xbox account, it automatically gave you a name, this was to avoid usernames filled with "xX"'s and those kinds of things, and that's probably your name.
Try going to Xbox.com and either put your e-mail there or TeleostDuke11, and then your password. If it matches then it's just your Xbox account, and from there, you can change the name.