Actually, we were discussing this in my journal a few days ago, and apparently all sorts of things happen with nodes. I had noticed, I thought, that clones always have alternate nodes, so when it comes to training, you don't have the parallel node option to work with. But right now I have two cuttings that are two months old and 12 inches tall, and they started with paired nodes and still have them. So it depends on the structure of the side shoot when we cut it? ... that had occurred to me ...
But some growers have seen plants with alternate nodes switch back to paired before bloom. And others are strain dependent. I've had a couple strains that never went alternate. Doesn't it seem like the bud structure is different, too? The paired nodes tend to produce large thumb-sized nugs at the nodes, with less popcorn overall.