Does deja-dup have some mechanism to detect when I've moved a complete folder into a new subfolder?
Or will it copy all the files in the folder again?
I'm talking about folders that contain some 100 GB of data, so if I do something the wrong way several times, my backup drive could easily run out of space without really needing to.
duplicity, which Déjà Dup is built upon on, does not have any such intelligence. Hence any moved or renamed files will be treated as new files.