General Krell demonstrates in Star Wars: The Clone Wars that the use of two saberstaffs is plausible:
However, is it advantageous in battle, as opposed to dual lightsabers or a single saberstaff?
As discussed in this answer, dual lightsabers limit your balance and movement. Additionally, your mind must focus on more objects, something even a force-user will find more difficult than using a single lightsaber. Additionally, when you swing a double-bladed lightsaber, you have to be constantly aware of where the other blade is to avoid cutting your own limbs. This is going to limit the range of motion of your attacks and defenses. While it may look cool, using dual dual-bladed lightsabers is not very practical.