title: Networkx duplicate edges
body: <p>If the same edge is added twice to the <code>networkx</code> edge data structure, will it then have two edges between the nodes or still just one? For example, would a spring layout show the nodes converge more with edges <code>[(a,b),(a,b),(a,b),(a,b)]</code> than <code>[(a,b),(a,b)]</code>? If I want to weight the edge, how would I go about it?</p>