even though the specs are the same (linux doesn't really care if they are or not), the network adapter is different. every NIC has a unique MAC address, and because of this, your system will assign it a new logical name.
you can find out what your card's logical name is by looking at the following command:
it will be listed next to "logical name" like so:
then you can edit /etc/network/interfaces:
$ lshw -C network
WARNING: you should run this program as super-user.
description: Ethernet interface
product: 82801DB PRO/100 VM (LOM) Ethernet Controller
vendor: Intel Corporation
physical id: 8
bus info: pci@05:08.0
logical name: eth2
width: 32 bits
capabilities: bus_master cap_list ethernet physical
configuration: broadcast=yes driver=eepro100 multicast=yes
resources: iomemory:fc500000-fc500fff ioport:1400-143f irq:193
and change your current settings to your new logical name:
gksudo gedit /etc/network/interfaces
in my case, i have to edit "eth0" so it reads "eth2" instead.
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
iface lo inet loopback
# The primary network interface
iface eth0 inet dhcp