At the moment I am working on a pattern out of the book Duchesse-kant, Kant voor Hertoginnen, by R. Delescen-van Rijsewijk.  It is a practice piece to improve my techniques.  In the leave I am working, you can see pins in the middle of the clothwork.  This is where extra pairs were added. In Duchesse you normally add pairs at the edge stitch, but It is less obvious when you do it in the middle.