Theres no real reason why you could not do an instance duplicate, but then you need to go in an attach all the peices of geometry to create a single tube. This would involve a lot of work, as all the NURBS seems would have to match up, more then likely the NURBS Curve would have to be rebuild to provide the correct level of detail.

I still say multiple NURBS circles and a curve, then lofting is the way to go. But thats just my opinion.