ExportToCAD is doing the right thing�??generating separate polylines for each boundary.
The underlying issues are:
1. AutoCAD doesn�??t have a true polygon feature so ExportToCAD must use the polygon boundaries.
2. To avoid making assumptions about what the user 'really' wants and possibly losing data in the process, all constituent polygon boundaries (known to the GDB) are exported �?? the result is multiple features stacked on top of one another.
Understanding what�??s happening
Imagine your feature class contains two polygons, one inside the other. Polygon A is the outer polygon. Polygon B is the inner. Polygon A has a HOLE where Polygon B is.
When you ExportCAD, you�??ll get THREE boundary polylines in the output CAD drawing. You�??ll get the outer boundary of Polygon A, the inner boundary of Polygon A, and the outer boundary of Polygon B.
If you do an identify on the outer polyline, you�??ll see the attributes for Polygon A.
If you do an identify on the inner polyline(s), you�??ll probably see the attributes of PolygonA�??because you�??re selecting the inner boundary of polygon A.
If you then ERASE that boundary�??you�??ll still see the boundary, because underneath was the polyline representing the outer boundary of Polygon B. If you now select that boundary, you�??ll correctly see the attributes underneath.
This is very similar to what you see when you use the FeatureToLine tool in ArcGIS on the same Shapefile.
Possible Workaround
One possible solution is to add an attribute to your source GIS data that identifies if a polygon is a donut hole or an outer polygon. You could then do queries on the feature class to pull out the donut or outer polygon and export the outer polygons to a CAD file, then make another query and export the donut polygons and append them t the same DWG or create a separate file.
The key is to figure out how to avoid stacking boundary polylines on top of each other. CAD-GIS integration isn�??t trivial, but sometimes understanding what�??s really happening helps us think about the problem in a different way. In short I would have to say that this is as designed and not likely to change.
