DUID of Mac mini changes

I have been running a dual stack network at home for a few months. DHCPv6 runs without issues. I have a couple of servers on my home network one of which is a Mac mini. I assign static IPv6 IPs to the servers according to their DUID. The Mac mini is the only device that changes between two DUIDs randomly. This means that the server goes off line for a period of time since it does not get the proper IPv6 address assigned to it when it changes its DUID. Then after several days it switches back to the DUID it had before.

I have no idea why it randomly changes its DUID. Is there a way to get the Mac mini to have a stable DUID like the other servers on my network?