Without being too geeky, every Ethernet card has i

Without being too geeky, every Ethernet card has its own MAC address. In theory they are never duplicated. So a computer that has a wireless card and a LAN (wired card) has two separate addresses. If they check by Mac address you can't take your laptop to another location, it would still recognize you. Laptop, iPad or phone different macs. Don't know what they look for but it is another way to track.