CREATE TABLE table_23402 ("Rd." FLOAT, "Circuit" CLOB, "City / State" CLOB, "Date" CLOB, "Format" CLOB, "Round winner" CLOB, "Car" CLOB, "Entrant" CLOB)

Which circuit has two heats as the format?
SELECT "Circuit" FROM table_23402 WHERE "Format" = 'Two heats'
SELECT "Circuit" FROM "table_23402" WHERE "Format" = 'Two heats'