I don't think this is possible at the moment but would be nice if it was......can we have an option to sweep a profile along multiple curves at once rather than having to do the sweep process for each spline. This probably wouldn't work with a 2 rail sweep in its simplest form as it would confuse things but if there was a button for a multirail sweep (below the 1 or 2 rail sweep option' which you pressed and then selected the rails then pressed ok it could save time for single rail sweep objects. It could be made possible for 2 rail multi sweep by selecting your pair of rails then pressing a 'next' button then select your next pair etc.

Does that sound like a feasible suggestion?

Currently im modelling a standing seam roof and having to sweep each seam as loft isn't appropriate in this case, and it's a bit of a chore!