That's something I've been presuming to be the case for at least a decade, and not just with fossil fuel companies (though they are a notably likely example).
It's extraordinarily safe to assume that essentially every notable corporation has, either as a part of its own PR department or through another company, resources dedicated to not only massaging its own online reputation, but to affecting the public perception of its industry as a whole, and that that last would require some amount of liaison and cooperation with other companies in the industry, to their mutual benefit.
With the potential ROI, they'd be foolish to not do that.