Note both front and rear wheels are mounted the same way. It must have a wider rear axle, if it tracks evenly with singles. The Australian pictures and Darrin's FM have the the rear single wheel flipped to maintain sufficient track width. Which with the missing inner wheel puts excessive stress on the rear wheel bearings.
On an after market 4X4 conversion like Jay Shapiro's sometimes a front axle can be selected with the correct width to run a wheel (with zero or small offset) that will keep rear track about the same as with duals and also track closely in the front, and maintain or slightly increase track width in the front.
All of which isn't usually possible converting a DRW factory 4X4 to SRW, even with flippable wheels.
Charlie