Database: apartment_rentals
Question: What are the booking start dates and booking end dates of the apartments with type code "Duplex"?
SQL: select t1.booking_start_date ,  t1.booking_start_date from apartment_bookings as t1 join apartments as t2 on t1.apt_id  =  t2.apt_id where t2.apt_type_code  =  "duplex"