You could edit the database. Not sure what you’re using, but in MySQL’s workbench, you can copy and paste the rows to create new report_cards (questions). Then need to check the id’s are all unique and changed the database id.
Similar for the report_dashboardcard and report_dashboard (bit trickier as the report_card references will be different).
Pain to maintain though as any changes would have to be done across all the new questions/dashboards.
You could just run mulitple instances of Metabase. Have one source instance and migrate the data from the core database to your multiple instances. Provided each instance has a different database connection, would work well.