that would explain why there were 2 giant heartlesses at the end of kh1The two aren't contradictory. Namine is Kairi's Nobody created when Kairi's Heart left Sora's Body. That means she's essentially made from Sora with the imprint from Kairi's Heart. Kairi's Heart left her own body however, thus raising the times it left a Body up to two. Thus, should Xion be truly Kairi's Nobody, then she's either created from Kairi's own Body and Soul or some other substance under some other occasion.
Namine is unrelated.