well this conversation has two possible explanations
1) it was a mistake on the writers part
2) many things in the star wars universe are opinions of there story teller. when episode III came out many books, comics, short storys etc. became confiltant with the moives and the moives and the ultamite star wars force because it is the vision of Mr. lucas not some 40 year old over weight guy writing star wars storys in his mothers basement.