There is an instance in my tree of second cousins marrying, and I don't like the fact that the great grandparents, who they share, are shown twice in the tree even though they're in my database once.  I don't know what the solution is, maybe logistically it's impossible to show them any other way, but I get a brain cramp whenever I try to imagine it. 

Is this how all genealogy software works? This is the only one I've used.  

I've attached the relevant portion of my tree with some very crude markings...