Sharepoint 2010 people picker

In Active directory there is just one account for user 开发者_如何学运维John Dlouhý, but in people picker I always get two results. Do you have any idea why this is happening ?

Name:                     Account name:

John Dlouhý               biz\dlouhy
John Dlouhý               biz\dlouhý

biz\dlouhy vs. biz\dlouhý If I talk to Active directory directly and request these two accounts they have same SID, to there is really only one account.