I guess you're trying to manage your databases through http://YOUR_SERVER_IP/web/database/manager. I'm afraid that you won't be able to duplicate the database through the UI for security reasons.
If you check the Odoo configuration file accessing to your server via SSH:
$ cat /opt/bitnami/apps/odoo/conf/odoo-server.conf | grep "db_"
db_host = 127.0.0.1
db_name = bitnami_odoo
db_password = ************
db_port = 5432
db_user = bn_odoo
You'll find out that Odoo uses a user called
bn_odoo to access the PostgreSQL server. This user is created without admin privileges. In other words, this user can only perform action on the database
bitnami_odoo, however it won't be able to create/delete other databases in the PostgreSQL server. This setup is just a way to enforce the security in the server.
The only way you can duplicate a database is to access the PostgreSQL database as "postgres" user (see https://docs.bitnami.com/general/apps/odoo/get-started/connect-postgresql). You can find the credentials to do as explained in this guide: https://docs.bitnami.com/general/apps/odoo/get-started/find-credentials-link-postgresql