CREATE TABLE table_24425 ("Week #" TEXT, "Theme" TEXT, "Song choice" TEXT, "Original artist" TEXT, "Order #" TEXT, "Result" TEXT)

How many weeks featured duffy as the original artist?
SELECT COUNT("Theme") FROM table_24425 WHERE "Original artist" = 'Duffy'
SELECT COUNT("Theme") FROM "table_24425" WHERE "Original artist" = 'Duffy'