For example can it track the ID of the browser (if there is such
thing), or the ID of the computer / internet session?
No,If you changed chrome user account and the gmail associated with it and didn't use any sync methods,all the cookies and data would be invalidated from the first user to the second,there would be no sure way for example.com to figure it ...
how is two people using two accounts on the same device different from one user using two accounts in the same device from the point of view of example.com?
Nothing. example.com may know that there is two accounts connected to itself on the same device and even know that accounts are open in the same browser, but can only guess whether it is the same person ...
tl/dr: It's definitely a plugin doing this, and is almost certainly a privacy-focused plugin that is trying to randomly
obfuscate your user agent and plugin list to hide you from sites
performing browser fingerprinting. However it is doing it very poorly
and I'm dubious that the people who wrote this knew what they were
doing. So while there likely isn't a ...
So it's only happening on that one computer, other machines don't see this, correct?
If it's only on the one computer, it may be a hosts file issue directing the library call to a compromised site. If it's on all machines, it may be a compromised library itself.
In times like this, you should look at the Assigning CNA.
As can be seen from Mitre's Request CVE page, Chrome is a CNA and thus they can reserve blocks of CVE IDs for themselves before a vulnerability is discovered. You can read more details on how this is done from this official pdf by Mitre.
In short, nothing is strange with the CVE ...