Hello Mike and Chris,
Firstly Mike you seem to appreciate that twin axle movers need to be a very different beast to a single axle, and Chris, your experience hints at why.
When a Twin axle is turned, at least two wheels will effectively be skidding sideways across the ground. If you have tried to do this by hand, you have the mechanical advantage of the distance from the wheels to the tow hitch, compared to the distance between the axles, typically 3 to 1. Despite this it needs a lot of effort to overcome the friction between the wheels and the surface.
A twin axle mover has to do the same job, but without the 3:1 lever advantage so the motor/gearbox power needed is much greater than for a single axle system, To achieve this and to prevent damage to batteries, tyres and switch gear, the motors need to be sequenced in the way Chris described.