Just for reference here's a page dedicated Ubuntu time management with a section on dual boot conflicts
https://help.ubuntu.com/community/UbuntuTime
The funny thing is, this all started as another one of my quirks -- time, so called.
I'm a 'detail guy' and I can't stand inaccurate timepieces. That's all I was concerned with -- the damn RTC clock in this Dell being several hours advanced, after every reboot. It bugged me soooo much that I went to the trouble of procuring a new mobo and installing into my 1-month old Dell refurb.
Now, that's a true obcession. LoL !

After having the same prob with the new mobo, it narrowed down the possibilities considerably, so it wasn't a total waste of time n' money. But, it did leave me scratching my head, until you steered me down the right path.
Who would have guessed that Linux machines summarily *assume* that you have your RTC set to UTC ?
And, who would have guessed that THIS Dell allows Linux to reset the RTC to UTC time ?
I have three Dell machines -- a 7010 desktop PC, and two D-series laptops. This 7010 is the only one that allows Linux to sync the RTC to UTC time. My *guess* is -- with this PC being a 'business machine' -- it's made to sync/change/reset the hardware RTC to NTP server time (either local network NTPs or over the web).
We have 10s of 1000s on these Dell 7010s in my workplace. So, maybe they're a breed onto themselves. I've never owned another computer, in my life, that's allowed the OS to change the RTC clock. Evidently, some do and some don't, hence the articles you happened to run across.
If you look in the BIOS on this Dell 7010, there are whole sections devoted to allowing your IT department (for instance) to manipulate every aspect of these machines. That way, they can maintain hundreds or thousands of these Dell PCs over their WAN, rather than having an IT at every property, and having to make changes to every PC, in every office, in every location, et cetera.
It only makes sense that syncing the RTC to whichever NTP would be included in the BIOS feature-set. At least, that's my take on the situation.

Thx, again, for the heads-up, Graeme !