Are you trying to copy the CDF itself (as edited with CIW - Tools - CDF - Edit) or a given cellview's properties (as edited in a Layout/Schematic/Symbol via Edit - Properties - Cellview)?
CDF exists at the Library or cell level - use cdfCopyCDF to copy these.
Database properties exist at the view level; they override whatever defaults may be established by the CDF - use dbCopyProp to copy these. The dbCopyProp command isn't restricted to operating on a cellview either (i.e. the object pointed at by geGetWindowCellView() or dbOpenCellViewByType() commands). It could just as easily be an instance, figure, net, etc. contained within a cellview.
Hope this helps!