Take a look at:
/etc/udev/rules.d/70-persistent-net.rules (the actual name could
vary, but ubuntu usually keeps it consistent between releases)
Once you connect a few wifi adapters, it's pretty obvious what it's doing. ;)
Regards,
--
Robert Nelson
http://www.rcn-ee.com/
Are you using DHCP or static IP?
A possible entry in /etc/network/interfaces can be:
auto wlan0
iface wlan0 inet dhcp
pre-up /etc/init.d/wpa.sh start
post-down /etc/init.d/wpa.sh stop
Vikas
In that case, leave the mac address blank and use the "DRIVERS"
parameter for wlan0... Assuming the 2nd wifi isn't a "wl12xx" based
device it should work fine..