The Latin abbreviation ib id. or ibid., followed by a page number means that the source of the material is the same as the previous source but on a different page. It can also mean a previous source (but not the source immediately prior) and will be used with an accepted diminutive form of the cite, and the page number.
Now, if the source is exactly the same as the previous citation, including same page, the writer would use id.
Style and Form manuals are essential to have around for anyone who communicates to a professional audience in writing. No one reads an article or a legal brief that is properly cited and says, "geez-what a prick, everything is properly cited - OCD much?" However, if the citations are loose, incomplete, missing a year, volume number, or page number, you can bet that some of the readers in the know will start to discredit the message because of the laziness of the writer or the mistake of the writer.
However, in the legal briefs and points and authorities I read regularly, the citations I see messed up all the time are ib id. and id.