Double normal vectors at the mesh edges at the midpoints?

Hi everyone,

I have to reorient the y axes of beams with karamba Orientate beam component. My new local y axes are the normal vectors at the mesh edges at the midpoints. Since some edges are shared, I have double normal and double beams. If I use Remove Duplicate Lines it doesn't work. How can I do? You can see attached the gh definition to find the normal vectors and the gh file.

Many thanks in advance!