i found the solution that I didn't know was the serial number issue
https://bitcointalk.org/index.php?topic=270367.0I have been using a Netbook with Windows XP SP 3 and it will allow 2 USB Block Miners, when I add 3 it says there is a dublicate device running on the system. It is not the miners because they all work and I have to have 2 on one computer and the other 2 on the others. I used the WinUSB drivers from zadig. it does this on my laptop with the internal USBs also. Is there something I am missing or another way or driver. I also use CGminer.