Deletion is not working properly
Make sure that everything works well when deleting a subject that contains copied datasets.
Is it working well if we delete the datasets from solr (but not the exam/acq) then the subject ?
Test all the possible ways of deleting a subjects and its content.

Change the error displayed in Job page when copying a dataset that already exists in a study

Add something to show that an entity is a copy or that it has been copied