As you can see Maya is not very helpful in this very simple need.

To be honest - this is a BIG and BAD surprise for me.

The offset command does its job very bad if you want a parallel copy of your curve so I imported the same shape from AutoCAD and than used DETACH which is good if you have less than 10 curves in your curve - and I lofted each each pair.

As you can see - I needed an offset (the red lines shw that the distance is consistent) and not a duplicate - because when you duplicate and then rescale - it does not give a similar distance between all the edges.

Anybody interested in a used Maya 4.5 Complete.. COL=Crying out Loud...)