People Picker showing same user twice

Hi All,

First of all I am new to SP 2010 FBA.

Please see the below scenario;

I created a web app which supports both FBA and Windows authentication. Then I created some users using the MemberShip Seeder tool in this web app. Now on I search the user using people picker the same user is appearing twice. One in upper case and the other in lower case. Whichever user I am clicking/selecting the exact user is only getting added. The issue is appearing only if I am searching with lower case. If I am entering names with uppercase letters, then everything is working fine.

So please anyone, provide your suggestions to resolve the issue.

Thanks in advance