I have had this problem before, and it seems to be related to Softex Omnipass.
Uninstall Omnipass, then reinstall it to remove the duplicated user icon.
On a different note, grab the Lenovo N200 fingerprint reader software for seamless integration with Vista. It'll work with your N100 Authentec fingerprint reader. It's also much faster to recognise your fingerprint. The only drawback is that you won't be able to store passwords for programs and web pages as you could with Omnipass.
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I uninstall omnipass,then after restarting username displayed only once but fingerprint logo is not displayed on top of screen with user names.After this i want to reinstall it but application file for omnipass is removed in uninstallation.So i used system restore.Because of this now user name displayed twice.How to reinstall omnipass?