Sync over Windows license possible?

I have a few Windows machines, and recently noticed that a couple of them were running the same ("retail") license key. Initially I was concerned that somehow they were both running the same license, and because of the source of these licenses (paid for, but not direct from Microsoft), that there might be other machines not belonging to me that were also running this same license.

I have been worring that somehow these other machines might be able to sync my machine somehow, and, for example, have access to the mailboxes that I have added on my Windows 10 Mail simply by virtue of being seen as the 'same license' by Microsoft.

Since then, I have discovered that the license key I have is in fact the a 'generic' Windows 10 retail license key, which many people on forums have reported finding on their machines - so it is not necessarily that I have the 'same license' as far as MS is concerned even though the code is the same (they should still be differentiated by the 'system ID' or something similar(?)).

But the concept is still floating around in my mind: is it possible if some scammy seller has sold the same license key to different buyers, that those machines could somehow potentially become synched with each other just because of the same Windows license, so that the data on them (e.g. emails on the Mail app) is not secure?

Apologies for the length of this question.