TL;DR - There is nothing to worry about, appears to be caused by something running in the background of the OS.
This is a very common "issue" with "Cisco" EPC products and it appears to be an underlying OS "feature" that causes this "issue".
The problem comes from the fact that "Cisco EPC" products are not actually Cisco at all, they're Linksys products which have been rebranded as Cisco products. If you were unaware since 2003 until 2013 Cisco was the parent organisation of Linksys, all products that Linksys had developed or had been developing were sold as Cisco products not Linksys ones. The problem with that is Cisco never redeveloped these products, nor did they care to they simply just sold & marketed them as Cisco products but the truth remains - they aren't.
You may be wondering why that's a problem? Well it's not a problem as such it's more a thing you need to take into consideration, as these are not Cisco products they do not run the "real" Cisco IOS whilst I cannot provide you with a data-sheet for this information (As Cisco have since retired the product, removed all data from the website with the exception of forum threads and EOL'd it) what I can provide is an example of another product with the same commonality.
If you're familiar with Cisco equipment you will have probably heard of the SF & SG family, these are "Cisco" switches, like the EPC line they're not actually Cisco switches, they are in-fact Linksys switches this is evident when interacting with the CLI - one example would be when trying to use the backspace key, on a "real" Cisco product backspacing works as you would expect but on an SF or SG switch it doesn't - you must hold shift in order to use the backspace key. Another example is the following command
boot system image-1 that command doesn't work on a "real" Cisco switch, take the 2960 family for example that command would actually be
boot system flash:filename
The overall point is these products aren't running Cisco IOS (Which isn't Linux) what they're actually running is another OS based on Linux which tries to mimic Cisco IOS as closely as possible (Hence my examples). This explains why the OS shows as "Linux", this also explains why the MAC is a Cisco MAC because it is technically a Cisco product it's just not made by them. However, you shouldn't be worried about this, it's not causing harm to the network at all, it just appears to be something that runs in the back-end of whatever OS these EPC devices use.
As I said at the start Cisco haven't and probably will never release a statement on this partly because of the products being EOL'd and partly because of the fact that it's not something which is affecting you, it's just built into the OS to run in the background for an unknown reason which we'll probably never know.
If you read this you will see the device directly supports Samba server (Which I believe you already know) this will be whats going on, as the post you linked said switching it off should "fix" it.
Disclaimer - I am not directly affiliated with Cisco, I do not work for Cisco, I do however work for a Cisco partner. Anything in this answer is not the word of Cisco it is the word of my own as an individual based on research I've carried out. Please do not take this answer to be the official answer to the problem as Cisco have not and probably will not ever release an official statement on the issue.