[bug]: Email is register-sensitive

[Katya Go]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

login by email is register-sensitive, i wait that [e-mail] will be same [e-mail], but it isn't

Steps to reproduce

1. login at [e-mail] >> one new user appeared in the admin panel
2. logging in at [e-mail] >> 2nd user appeared in the admin panel.
   FR: received two e-mails to the same e-mail address and there are two users in the system
   Expected result - both logins will be ones user in the system

Environment

Production

Version

Self-hosted