CREATE TABLE table_20466963_13 (guest_2 VARCHAR, presenter VARCHAR, date VARCHAR)

Name the guest 2 for colin murray 6 april
SELECT COUNT(guest_2) FROM table_20466963_13 WHERE presenter = "Colin Murray" AND date = "6 April"
SELECT COUNT("guest_2") FROM "table_20466963_13" WHERE "6 April" = "date" AND "Colin Murray" = "presenter"