I left it blank. I was of the view that if wrote n/a in given name box, might it would become part of my given name for imm. purpose. So, i left it blank.
Background Declaration Document: 2 boxes for given name/s = Just 1 box dont put N/A on the other. You can have 2 first/given names like. Miguel Anghel Cotto so put the Miguel then Anghel on the second. or Mary Anne Magallanes.
I just literally followed CICs instructions. I didn't try to make any meaning out of the instructions. The instruction asks us not to leave any box blank. So, made sure the other 'first name' box is not blank. I used my first name in the first given name and the second one I entered N/A.