I'm not sure how effective their tests really are. I apparently am unique - no others found.
Apparently my browser UA is unique: odd, since it's a standard FF "out of the box" that millions of people must use.
HTTP_ACCEPT - another "out of the box" setting I would expect to be very common, yet noted as unique.
For this one excercise I enabled cookies - I usually prohibit them - so I got a Yes which apparently no one else has.
So based on that I should, in theory, match millions of other browsers, not the zero I was told.
There are many more headers that could have been checked but weren't: I block innumerable bots and hackers using various combinations of them.
The one thing they didn't pick up, which of course on a first visit they couldn't know, is that I have a fixed IP. Now that certainly identifies me within the limits of the two people and three computers at this location. :)
To be fair, I think their database was not working and probably the web site itself was stuffed: it just sat there loading at me most of the time. Out of five attempts to access the site I only got the home page twice and hence two (identical) "valid" tests from that - VERY slowly. This does not alter the fact that they do not seem to test all possible information and are completely fooled when JS is turned off.
Moral: turn off JS; turn off cookies.