Hi Graham Paull,
I had uninstalled and installed the unique plugin for MOODLE2.8+. Installation went successful. I had done all the needful configurations as in the plugin documentation, but I could see the same as before :: users can lo-gin by multiple attempts.
I am using "Email-based self-registration with admin confirmation" authentication.
Could you help me with your suggestions.
Many Thanks
Lavanya Manne