Basic Problem: 3D Line Drag, Number of Elements

Hi. I have only started using HyperWorks in the past couple of weeks for a university project and have a problem that seems silly but I cannot solve.

I have a 2D mesh that I am trying to make 3D using the 3D line drag option. I have selected the surface and set the drag to 1 and line list to a line in the z-direction, which should just extend the elements from 2D to 3D. My problem is that when I do this, it doubles the number of elements in the model which I have been told should not happen. I'm sure the answer is obvious, but can anyone tell me why this is happening?

Thank you.