Even if 4000 years before, i didn't see any drastic changes in technology. I am a nerd, y'know. I would know.
The two bladed sabers are, in general 2 sabers joined by their back, powered by a single energy pack. If you cut it right, you could ruin it (With sunder feat, of course). If you can't cut it right, one blade can still function (It is not cut in half in the movie, 3/4s of it still remains) . Even in KotOR. Sabers in KotOR are not in any ways different from other eras (maybe some crystals).
Double bladed sabers are written in Star Wars RPG game from WotC. It was in 3E, but somewhat changed.