Open Multiple Drawings in one Instance of Draftsight

When we double click on a dwg file Draftsight opens and displays the drawing.  When we double a click on another dwg file a new instance of draftsight opens and displays the drawing and then the first instance of draftsight opens the file again.  It would be quicker if it would just open another drawing session in the same instance and not try to open another.  Is there any setting that would make this not happen?