Wan on eth1 and Lan on eth0

I have a local network on dev eth0
Server has static IP of 10.0.0.1
Gateway is 10.0.0.1
and Dns is 10.0.0.1

I am using this network for imaging 500 plus computer...

Now, Issue that I am having is that I need to update packages and I dont want to change the configuration on eth0 because I dont want something breaking out on my imaging system...
the server has two nics and I want to use eth1 to connect to the internet, the only issues is, I got no clue how to do it without messing my network which I need it to do my daily job...

OS CentOS 6.3