There is some confusion as to what the
Consolidate and the Duplicate functions
of Final Cut Pro X actually do.
I use both of these functions in a detailed walk-through of the workflow to archive a group of projects to an external archive HDD.
By using the “Duplicate Project + Used clips” option, I am able to archive a group of projects into one, then consolidate all the media and archive (duplicate) to another location and remove any clips that were not used in the project, hence saving disk space in the process.