In looking at print material, do you make certain there is not some sort of addendum stuck at the end of the book? A book of marriage bond transcriptions I recently used had two pages of "missed" entries that were added after the book was typed. These pages were not included in the index either.
And microfilmed church and other records may have extraneous material filmed after the book or actual records were filmed. And sometimes the pastor might insert something extra at the end just because he felt like it.