Well, in the Manga, there have been at least 194 nights, hence the chapters. Plus, there have been major time jumps between story points. Remember, though: Kanda isn't the brightest crayon as it were, so he seriously may not remember Allen's name. Just the one he gave him. However, I think he seriously remembers, he just likes to call him that because he knows it makes Allen angry. Believe it or not, Kanda does have a sense of humor. To a degree. =3