I don't see why not unless they don't fit.
The load is never perfectly balanced anyway and the design and hopefully installation take this into account.
My asymetrical's columns are mounted squarely facing one another with arms of differing lengths causing the asymetry. I've also seen lifts with columns angled away from one another, if differing length arms the swapping on those would present a problem.
While I don't recall backing a car onto mine(I probably have) I don't see any reason not to without swapping the arms. I've lifted loaded contractors vans that are WAY heavier in the rear* without problem so putting the heavy end of a car on the long arms wouldn't concern me.
* Sometimes, once lifted I'll use tall jack stands at the bumper on these too.
Positioning has a lot to do with available lifting points. The same car can be positioned differently according to where you lift it from.