IAW's numbering system is a mystery. Sometimes they will re-use a number for a duplicate item, and sometimes duplicates will each have a unique number. Other times, a number will be re-used for items that are only sligtly similar. Then there are the strange cases where a set of duplicates will each have unique numbers except a few that will be grouped under the same number. Some listings have an "S" after the number, and one has an "r", but I have no information about what those mean.
In week 36, they listed every item twice, and then listed two completely different items as #372, yielding four #372 listings for that week, and generally screwing up my whole afternoon. I think the scanner is supposed to be #5106 based on the image names, but I just left it and wrote a note in the comments.
IAW will sometimes change the images used in past listings, for new listings. This means that the old listing's pictures are different on those eBay pages.
Overall, the system that IAW uses for managing and posting listings seems very unsophisticated. I think they are just copy-and-pasting from MS Word leaving many Office related artifacts in the description text, and writing in the image names each time. There are often slight mistakes, usually in referencing images, that have lead to the high number of canceled listings.