Well, from what I understand of these kinds of suspensions, the torsion bar IS the spring part of the suspension, at least for the front anyway. Our torsion bars do for the front of a VX what the rear coil springs do for the back as far as lift, so unless one of your torsion bars broke and was replaced by a more worn torsion bar that required more adjustment to achieve the same amount of torsion/lift, my first guess would be that someone just installed it wrong. An example of that would be the difference a person would get if they installed a torsion bar with the vehicle sitting on the ground as opposed to installing one while the vehicle was on jack stands with the a-arms hanging down.
That's just a guess on my part though and is the best I could offer without knowing the actual history of work that's been done on your VX. I suppose it could also be that you just got two torsion bars in the factory that weren't rated exactly the same torsionally and that this is a more common occurrence in our vehicles than either of us are aware.
I think the only way to know for sure if one of your torsion bars is more worn than the other would be to take them both out and reinstall them under the same conditions on both sides.