in the “Visitors > Visitor log” do you see the requests? what URL do they have? maybe the other website has copied your code into their website? in which case you could contact them and ask to remove your code.
IPs are from a variety of different IP addresses and countries.
Presumably you mean they might have copied my Piwik tracking code onto their site somehow. I’ve tried looking for it but came up empty, however, it looks like they use a lot of JS and 3rd party web services on their pages.