It might also be helpful to have a look at this post:
https://www.thebuddyforum.com/honor...y-privacy-keeper-post1423190.html#post1423190
Especially in regards to the following, if you run several accounts on one machine:
"d) hkcu\software\blizz*/battle*/wow
key "licenses"
unique by account/sub license
length grows with every account you log in"
So what it looks like to me is that blizzard stores in your registry, some sort of hash of whatever kind of "license keys" are unique to your account. And probably passes that information along to their servers when you log in. When they investigate, that would make it pretty easy to tie accounts together, and also easy to spot new accounts created by the same person as long as that registry value is never cleared. Just looking at the information stored in the registry according to that post, to me, sheds a lot of light on some of these "Why do I keep getting banned how do they know it is me?" posts. And would also explain why logging in from a different IP address might be ineffective at hiding your identity.
Of course, I don't have any special insight into Blizzard's methods of bot detection beyond what anyone else here knows, so I'm just speculating here, but man that sure is more than enough info to identify a user, isn't it?