Database: apartment_rentals
Question: Return the booking start date and booking end date for the apartments that have 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"