I've heard conflicting information from various people.
One camp I've heard from suggests that putting 2 mines on a deposit and mining it twice as fast is an exploit. To the extent that even if they're owned by 2 separate people, it can still be considered as such.
The other suggests that it's intended, as it hurts planet stats and if you're willing to fill a city with mines and pay the costs associated with that, then it's how it's meant to work.
The rules suggest the latter ( http://www.swcombine.com/rules/?Mining#Building_a_Mine_(Preparation) ), but before doing it, I wanted to check that the rules weren't out-of-date and that the former was actually the way it's currently viewed.
I have a city that has 6 mines on it.
Why TSK originally built it that way I have no idea, seems like an awful waste, especially when it came up rockivory when they pulled all of the quick quantum out.
If it is your city you can do whatever you want on it.
82 slave markets to mess up the entire planet for everyone else? Its a feature, not an exploit.
Not an exploit, I'd say. There's a cost associated with making too many mines, and although they can be removed later there it still has an impact until then. The balance specifics might not be perfect in this regard but I don't consider that abusive at this point.
"On two occasions I have been asked,—"Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."
- Charles Babbage