No, they're unique. Each manufacturer is given a block of MAC addresses, and they assign them like serial numbers to each NIC they build. Each cell phone, WiFi

No, they're unique. Each manufacturer is given a block of MAC addresses, and they assign them like serial numbers to each NIC they build. Each cell phone, WiFi access point, and normal NIC, has a unique MAC. If this were not the case, if two devices had the same MAC, the risk of a network collision would exist, and manufacturers, aware of this risk and the damage it would do to their reputation, act to prevent it in their own interest.