I think the MAC address is stored in the config mtd partition (at least that's how it is on the N8x0s, retrieved by /mnt/initfs/usr/bin/wlan-cal and set via /sys/devices/platform/wlan-omap/cal_mac_address at boot time) so it's theoretically possible, however unlikely, that it's the same device flashed with a new config. It doesn't say anything about the chip in any case.