From what little time I did spend with
Cynorkis fastigiata, it seems as though what you experienced is the norm in the species, they appear to multiply rather easily and quickly compared to their cousins Habenaria. From one blooming sized plant, I got 2 good sized tuberoids on it. There's probably a good reason why Andy from Andy's Orchids priced this species so cheaply, and it is most likely that the reason is in part what you described and partly what samarak described. I've even seen flasks sell inexpensively as well.
Seed set is 100%. Not a single seed pod aborted. They're self fertile, and if I'm not mistaken they're autogamous. They're really aggressive reproducers.
I know
Cynorkis angustipetala is starting to show signs of what you mention, (rapid division). I originally started with 1 large growth, I now have 2 large tuberoids. Keep in mind, I haven't even grown
Cynorkis angustipetala for very long. So, yeah, if your
Cynorkis fastigiata is doing that, then that's pretty awesome!
Cyorkis fastigiata are really cute plants.
I guess my point is that, what you're observing is typical of the species
Cynorkis fastigiata. They are sturdy plants, (for a terrestrial orchid that grow root tuberoids), that asexually multiplies easily and rapidly in cultivation, and sexually reproduces with a very high success rate.