Jetson Nanos have same MAC address

Following Jetson Nano have same Mac address. I want to the reason and how to modify the MAC. Thank you.
These S/N are:
1421919093857
1422019011221
1422019026980
1422019011637
1422019013436
1422019013442
1422019011229
1422019012175
1422319052412
1422019011127

Hi Harris.li,

Issue found on A02 devkit, right?
This old issue comes to my mind. I think it is duplicated with your problem.

https://devtalk.nvidia.com/default/topic/1056705/jetson-nano/jetson-nano-developer-kit-ethernet-firmware-update/