Please don't map for the renderer by adding pretend dual carriageway segments where no physical lane separation exists.

See https://wiki.openstreetmap.org/wiki/Dual_carriageway :
"Roads are *not* to be mapped as dual carriageways if the two directions are only separated by paint. This includes single or multiple painted centre lines, hatched areas, channelized turn lanes, two-way turn lanes, by flush medians, or by any other means that is not a physical barrier to vehicles."