I know of one overlapping road in England: Tinsley Viaduct
by Sheffield. The Motorway runs over the top of another road, yet in Cartouche the minor road is shown be either side of the Motorway. I'm not sure if this is 'proper' though Google maps also does the same
, as does Bing.
If navigating from A to B using either road, the client should keep you stuck to the appropriate road. If not navigating, then you might bounce on to the wrong road perhaps, but maybe that doesn't matter?