To have a clean network installation you should clear all network preferences. Open Preferences -> Network. Delete all Network Services/Ports (with the Minus "-" sign). And then delete the following preferences files:
/Library/Preferences/SystemConfiguration/NetworkInterfaces.plistTo explain why this could be necessary for you I will tell you my case. I installed the Mac OS X which I'm using with my Chameleon-EFI Mac on my MacBook Pro (external USB-drive). The MacBook Pro has 1 Ethernet, 1 WLAN, 1 Bluetooth and 1 Firewire Network Service/Port. My Chameleon-EFI Mac has 2 Ethernet and 1 Firewire Network Service/Port. After the first boot it showed in Preferences->Network: 1 Ethernet, 1 Airport, 1 Bluetooth (all from my MacBook Pro) and 2 new Ethernet ports en2 and en3. I wanted to have the 2 Chameleon-EFI Mac ethernet ports as en0 and en1. To do so I must delete all the old stuff from the MacBook Pro.
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