Hi. This is all your router's doing, not Sonos. 

Are 64, 66, 69 and 108 the components of a Home Theatre setup?

Yes with the Beam

The Sub and surrounds connect via the Beam, not directly to the network. Your router is having difficulty seeing the Mac addresses so is proxying the Beam's MAC address to the other components.

I don't think this would cause network issues.  The components have unique IP addresses. I am not sufficiently expert to say with total authority that this is not a problem, but I don't think it is

It certainly kills being able to reserve IPs.  However,  I’m not 100% sure it causes negative behavior's. 

What negative behaviours are you experiencing? 

Disconnects of certain devices.  Sonos devices appearing and disappearing. 

You can still reserve IPs for your Sonos, just use the dataplate’s MAC to set it up. 

Not sure if that would cause your router glitch to go away or not though.

Once assigned power down all Sonos and reboot the router, then power the Sonos back up. This should clear any cached IP and MAC data and give you a clean and stable start.

Which model router are you using?

That will take a while as I have over a dozen Sonos devices.  But I will try.  What I did just try is to enable IGMP proxy on my Orbi.  I found some threads about this reducing traffic due to Sonos multi-casting.  

My router is Netgear Orbi RBRE960 with two Sats

Are you using SonosNet, by having a Sonos device wired to your router?  Running a mesh WiFi with Sonos in WiFi mode would almost certainly give you problems.

I stopped using SonosNet due to interference.  Moreover,  not all Sonos devices use SonosNet anylonger.  i have three Moves and my newer Beam will not use SonosNet. 

Full disclosure: I don’t have any ORBI experience.

If you don’t want to reboot the SONOS players, you could make the router reservations and wait a few days for all of the clients to renew their IP addresses. You probably will not be able to reserve the duplicates. After making the reservations, reboot the router and check to see if the duplicates are still present. Maybe you can make more reservations at this time.

I had a similar duplicate issue on my ISP’s FIOS router. After searching for discussions about this router, I discovered some “fires” are burning. While I’m not real happy to being stuck with this router, it’s working well enough that I don’t want to go through the trouble of replacing it with something else (this would require some effort). Reboot and reserve cleared the major issues for me. As a hedge, I will occasionally reboot the router.

IMO it would be better to deal with the interference than to abandon SonosNet. The fact that not all devices can connect to SonosNet does not mean that none should. Why would your Beam not connect to SonosNet ?

But your call,, obviously. 

So,  one thing.  I realized before I said everything except my moves and one HT didn’t go over to Sonosnet before I abandoned it.  So,  I gave Sonosnet (my Boost) another shot.  Still,  one of my Beams,  its Sub and its Surrounds still remained on my Wifi (WM: 1).  So,  I removed the Sub and Surrounds from the Beam -- turned them all off and on.  Wouldn’t you know.  They all switched over to WM :0.  I’m thinking maybe this was at least part of my issue.  If that Sonos mesh cluster remained on my Wifi I’ve seen postings about Orbi STP and Sonos STP not playing nice together.  Now,  only my Moves remain on Wifi and I never (usually) group them with anything else (even if I still can).  This is a theory but I’m going to let this soak for a handful of days and see if everything clears up. 

I’ve been far happier on SonosNet with a wired speaker than WiFi as it allows me to use all the options my WiFi offers without having to restrict myself to a configuration Sonos supports.

I don’t have a Move or Roam, mostly because I don’t want to go back to Sonos over WiFi. If I did get either I’d buy and configure a dedicated Access Point for the Sonos gear to connect to.

@Will307 . I'm glad you are giving SonosNet another shot. SonosNet isn't  a panacea, but mesh wifi systems have a variety of features that can hamper Sonos, particularly when grouping speakers connected to different mesh WiFI satellites. 

Thanks all for your help and attention.