With olympic-style weapons, yes, it might be; I've only fenced with olympic weapons twice; they are light, usually taught 1-handed (the off hand used solely for balance), and taught with a 1/4th on stance (body center line points 75 degrees off target; sometimes as much as full-off aka 90 degrees...). And they react NOTHING like a rapier, let alone a broadsword. More on that later.
With historical baited rapier, no, it isn't, since the open hand is used as a parrying device as a default; you can't do that save in 3/4 on to full-on stances. The second weapon thus makes far, far less difference.
Double-Epee (AKA Musketeer), triple-Epee and Schlager are fairly close to baited rapier in weight, but the response is somewhat different. I have an oval-schlager, 40", that I use as my off-hand sword, with my hanwei 36" practical rapier (a baited blade with a built in tip blunt). I've used a wide variety of practical rapiers and schlagers... oval and diamond, 34" to 44"... I've even used a baited shamsheer. None of them felt like the double epee, and it felt nothing like the foil. Them foils will teach a man deadly-to-himself errors...
For historical broadsword C&T, two weapons is the norm: Sword and Shield is the default taught technique; single sword is derivative, AND the biomechanics prevent much adjustment if one is to maintain the power swing. Twin swords versus sword-n-board is not much adjustment, but it is an adjustment. Twin swords is actually easier than sword and dagger, however! (With twin swords, you just alternate coil-recoil/molinet, and you can get incredible amounts of hurt going. Spectacular to watch, bloody fast, and you can wind up being hit several times before you can fall! I've been on the receiving end of this ONE TIME... Sir Phelan Swordbreaker, KSCA, beating me mercilessly... and it is capable of rendering a concussion through the heavily padded 14ga steel helm.) I know three guys who can do it, two of whom are also Knights within the SCA.
I've been fortunate to get to observe several of the best KSCA's training sessions on combat biomechanics; they overlap Tattershalls' fencing biomechanics. Both match the biomechanics of Kendo fairly well, too.