I've seen this one a few times. Usually it boils down to the fact that the solo rate is simply the cost of the plane, while the dual rate is the solo rate plus the cost of having an instructor. Pre GFPT, the instructor MUST stay on the ground at the school, or in the local training area. They cannot go home, or on a Nav, so you are most likely paying a Dual rate in order to pay for their time.
Even if we aren't in the plane, we're still responsible for you
