Won't protect against an offline attack (just will confuse the hell out of the hacker) but might confound an online attack? Until someone gets wise and runs the tool a second time. Loving the chaotic neutral vibes here.
It doesn't really even protect against online attacks though. Like, if you're going through a list of known accounts, by definition it won't be any of those accounts' first time logging in, right?
And if you're not going through a list of known accounts, good luck getting anywhere with your attack any time this millennia