gas-chamber. I'm interested in what makes you say that. I don't know of any contracts that are let out to two companies to operate together. Sure, there are ad-hoc charter flights on top of contract flights by another operator but I am not aware of a mine contracting two companies to go fly to the one mine.
Having said that, I'm totally prepared to be proven wrong.
I have heard of mining companies letting out contracts to seperate contractors for similar but not exactly the same criteria (ie, mining equipment/ongoing maintenance) but not the fly-in fly-out servicing.