The yEd graph editor supports multiple labels for an edge. Creating the first label for a selected edge is conveniently achieved by using [Edit Label] in the [Edit] menu (or F2 [Mac OS: Enter]) and entering the label's text.
You can add further labels to an edge using [Add Label] from the edge's context menu:
Multiple edge labels are used in several kinds of diagrams, for example to annotate the multiplicity of relations in a UML class diagram.
In this example the labels "1" and "1..n" are the multiplicities. They are just two labels of the edge. The labels use the standard label model "6 Pos". (They were moved to the beginning and the end of the edge using drag and drop.)