The spell is in two parts, right and left hand, and each does something different.
A spell tome can apparently teach only one spell. But I see that many spells have three definitions...one using the left hand, one using the right hand, and one (presumably for dual casting) that uses both hands.
As long as they all use the same name in the "name" field, are they all taught by the same tome? I would think so, but I'm not sure.

