Hi guys. I did catkin_make again and I got 3 of the same error. That is:

CMake Error at /opt/ros/groovy/share/dynamic_reconfigure/cmake/extras.cmake:58 (add_custom_target):
  add_custom_target cannot create target "pcl_ros_gencfg" because another
  target with the same name already exists.  The existing target is a custom
  target created in source directory "/home/gordon/catkin_ws/src/flight".
  See documentation for policy CMP0002 for more details.

CMake Error at navigation/voxel_grid/CMakeLists.txt:28 (add_executable):
  add_executable cannot create target "voxel_grid" because another target
  with the same name already exists.  The existing target is a shared library
  created in source directory
  "/home/gordon/catkin_ws/src/navigation/voxel_grid".  See documentation for
  policy CMP0002 for more details.

CMake Error at hector_slam/hector_geotiff_plugins/CMakeLists.txt:75 (add_executable):
  add_executable cannot create target "hector_geotiff_plugins" because
  another target with the same name already exists.  The existing target is a
  shared library created in source directory
  "/home/gordon/catkin_ws/src/hector_slam/hector_geotiff_plugins".  See
  documentation for policy CMP0002 for more details.

I know of one solution that is to use catkinmakeisolated to prevent these from happening but I was told that it will make the whole thing work slower.

Anybody solved this before?