If they are made public, will another country investing in another one (or even a bigger one) discover anything that the European one hasn't?
Yes. CERN is a publicly funded, shared facility; its users are universities. What it does has no direct commercial value.
> will another country investing in another one (or even a bigger one) discover anything that the European one hasn't?
Possibly. The proposed machine would allow more precise measurements of the Higgs boson's properties than the LHC. The best case scenario is that those measurements would turn up deviations from the Standard Model, which would point the way to something new.
To actually "discover" that hypothetical new thing, in the sense of directly detecting a new particle, would probably require yet another accelerator to be built (possibly in the same tunnel).
Well, apart from that "web" thing.... ;-)
I always think that was a great example of the complete unpredictability of research - fund one thing and get benefits you'd never have been able to predict.
It took off because it was free, open source and easily portable by design, but frankly, pretty much the same thing could have, and doubtless would have, emerged from many other large organizations with similar requirements (quite possibly an intelligence service like the CIA - let's not forget where Tor came from), even without a dime being spent on particle physics.
As for direct commercial value, CERN made it freely available to all, as it must. The closest it got to making some money off it was an Apple program to donate computers to the office of documentation.
What a second LHC does is allow you to verify results independently. With one LHC you have to be extra careful about assumptions you made and what data might be being thrown off by local peculiarities.
Being at the forefront of particle/energy research is it's own reward. The results are only part of the prize. Learning how to build a LHC is probably just as valuable.
https://home.cern/science/experiments
They just happen to feed off the same particle beams.
The proposed Chinese collider would not be a second LHC; it would be a Higgs factory for precision studies rather than a discovery machine like the LHC.