Thanks both for the suggestions but it's not exactly what I need. It's a litte difficult to explain 'cause English isn't my native language and I used a bad example I guess :). But here a new one. It's possible I have to deal with those shapes. So I those lines to be evenly distribute between the paths. So there's no overlapping and an even spacing. In the first one I used the outside path as 'rail' in the second one the 'inside'.