Beckett and the Standard Catalog have a tendancy to number everything, regardless of whether the cards were numbered. Most of the time, it's just a matter of them alphabetizing an unnumbered set, and then numbering it accordingly. As a result, a lot of people (myself included) just get in the habit of duplicating the numbering they find somewhere else. I'm trying to work myself out of that habit and have also requested the ability to edit card numbers after the fact to help clean some of that up. I agree that we should try to be as faithful to the actual card as possible when documenting checklists.