Reset password will reset all users with the same email address. So if two users with different usernames but the same email address exist, then changing the password for one user will reset the password for each of the users with same email address.
Possible solutions
Have a check when registering to see if the email address already exists
Reset password will reset all users with the same email address. So if two users with different usernames but the same email address exist, then changing the password for one user will reset the password for each of the users with same email address.
Possible solutions