Sat Oct 11 2003 23:19 Four Turtles In Two: Remember the two-headed tortoise? Well, there's a two-headed turtle right here in the Bay Area. The pet store in the Serramonte Center in Colma has a two-headed turtle in a tank, along with a pair of Siamese-twin turtles. You can go in and gawk, and not pay a red cent. Pretty cool; there are also single-headed turtles, iguanas, guinea pigs etc., as in other pet stores.