Thanks z-vap. I'm not sure what I missed. Maybe I didn't reboot after loading Ext2Fsb. I thought I had but that's the only thing that makes sense.
I don't really know if the serial number are tied to the MAC addresses but I wouldn't think they would be. I think running multiple DSMs would require changing the MAC address and serial number, but also if you want to make the DSM available on the internet.