Lofting multiple curves to get different funnels

Hi all,

I'm new to grasshopper, so hope u can help me with this,

I have a bunch of curves in level 0, and another bunch  let's say in +5 meters, so I divide closed curves into different points, then I join the points making lines.

With the catenary component, I get a new bunch of curves that are gonna be lofted to create a funnel.

The problem comes when I loft every branch. The data seems ok because every operation is made separately, but  everyone of this lofts has 2 lines with the inverse starting point and ending point.

Why is it happening? all the lines are created same time and same way...In the image below you can see the flip during the loft.

Thanks for your time!

Ricardo