add some character before ad domain name in sharepoint

Hi everybody!

I had a problem in sharepoint 2010 and now in sharepoint 2013.

When I add a user with ad account sharepoint add i:0#.w| before the ad domain name.

so when I go to site permissions I see it

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Why it happens?? how could solve the problem??

I remember that in sharepoint 2010 it create some problems in my site permissions, and now I have problem in sharepoint 2013.

Thanks in advance!