@Royalist

Short answer ... maybe, but not as far as i know.

Long answer: Garmin calls it Unit ID (UID) and like a smartphone's ESN it's permanently written to the device at manufacture. Garmin's OS is quite opaque to us however the UID is plainly written in the device's GarminDevice.xml file. The UID can be easily changed in it in the same way that any plain XML can be amended, but then the device will update the XML on the next boot cycle and will write back the original UID. It's generally accepted that the XML is written from encrypted details held in the device's non-volatile memory region (usually region 41 or 154). We can decrypt and alter the nonvol information... however AFAIK it's not publicly known how to then, successfully permanently, write back altered and re-encrypted data to the region. Many of Garmin's regions are as opaque as to specific purpose. Even if we completely erase the nonvol memory, some data is automatically reconstructed properly when the device is rebooted. Therefore, it's reasonable to assume that essential data like the UID along with registration codes etc. are permanently held elsewhere on the device as well.