Simplicity is best.
Nothing prevents you from mechanically linking side stick controllers to translate control feedback from one side to another.
You can still have your Airbus style resolvers/input potentiometers on each stick, with the added redundancy that if the electrics in one side stick assy fails, it can still be flown normal, as the inputs are mechanically translated to the other side.
If you're set on approaching this from a purely computing viewpoint, I think your best bet would be to grab a pair of PC force-feedback joysticks and write some custom code to translate inputs from one into feedback into another (there's lots of Open Source force-feedback APIs out there).
However, such an approach would be miles away from the redundancy, accuracy, and practically required for serious use in aerospace applications.
Also, Google up some images of a complete Airbus side stick assembly - it's very much a mechanical marvel just as much as it is an electronic one.