The graphics viewing problem apart, this relationship of when siblings of one family marry siblings of another family creates all sorts of interesting situations.
Such as: When the children of two brothers (of say a Smith family) marry two sisters (of say a Jones family) then their children are parallel (or ortho) first cousins and they also are double first cousins. Genetically these children inherit from the same gene pool as if they were siblings.
Now if a Smith man marries a Jones woman (from above example families), then their children are also double first cousins, but they are cross (not cranky!) cousins.
Isn't genealogy fun?