ip blocking two pc

Hi, I want to write about a problem that occurs in my web. when his brother also wants to play on a server Escape
The problem only occurs on the server so I think that you can unlock it. The point here is that only one person can play with the internet. Also, I made an error, please see the picture below
http://www.fotoszok.pl/show.php/1167404_escape-error-ip.bmp.html

Try to connect again, or don't use 2 or more client for vote-kicking people