you just have to put the same table twice in the relationship graph with different names... than you can create both relationships...
table occurrences are like views of the table, it is normal to have the same table many times on the graph
Highlighting a specific term in Mystick's post so that you can learn about and understand the concept,
the term you'll want to read up on is "Table Occurrence". It is a different concept than (though based on) a "Table".