Posted on: 2014-04-04 10:55:00.000I'm not entirely sure how, since it was just a little hiccup for me. However, my best guess (I know, but "guess" is all I have now), is that, at least, LastPass — don't know about the others (and there's another rub)— would probably not have had that problem if you had ordered the fields on your registration page like so:
Email (This is your Username): __________
One mo' time on the Password: _________
Display name: ____________
Of course, this is just swapping the current "User name" and "Email" fields. I would swap those field because I think that LastPass guns for the first two fields (or the first "text" type field and the first "password" type field) — but again, just a guess.
Another way to do it would be not to have "Email" be the username, but to have your current "User name" field be the username, and then the "Email" field would not be part of the sign-in any more. However, the advantage of the current design is that your site can have multiple users with the same "User name" (what I call display name), and also it affords the facility of the user arbitrarily changing their display name (e.g some people would like to change their names on other forums, but it tends to be difficult or impossible to accomplish by the admin, because it's a "key" field, at least for the sign-in).
Hope that makes sense. Best, -Rick