In my case, I have pentaho connected to an oracle database.
To solve my problem I have followed these steps:
1. I have made a copy of my files from the home and public folders.
2. I have exported the analyzes and connections to the database.
3. I have stopped pentaho.
4. I have emptied the contents of table DS_REPOS_DATASTORE and FS_REPOS_FSENTRY.
5. I have started pentaho.
6. I have deleted the files, connections and analyzes (if you can not delete the analysis it is necessary to edit the analysis and upload a correct one and it will be deleted)
7. Import everything again, now it only appears once.
If you do not have pentaho connected to a database, I think it is only necessary to delete the contents of the directory:
pentaho-server / pentaho-solutions / system / jackrabbit / repository
Do not forget to make a copy of the files, connections ... since it will eliminate everything.