“Pickups with six tires have been around for a long time.
This is just a slight variation.”
Mechanically the tandem arrangement, especially if all four wheels are powered, is a lot more complex than a dually.
I couldn’t tell from the pictures whether all four of the tandem wheels are powered.
The headline calls it a 6X6, and the article refers to locking rear axles (plural), so I’d guess that all four rear wheels are powered. Of course, the Daily Mail writer might have been wrong, too.