yay! i hope it worked smoothly for you! we just had the one left over after getting a Hamm Bank & I didn't think i really needed either of those one point thingys.
It was an on the cereal box promo that Kellogg's was doing - mostly over the summer when Toy Story 3 was released at the movies. They would give you codes to use towards items/movie cash certs.
Yes, the codes were unique & could only be used once.