It's possible that the ID number is the one she got from filing the UCC-1. I used to work for my state's Department of State where we would put the UCC-1 forms that were submitted on file and issue a file number that was similar to her ID. The main significance of that number was that the UCC was filled. Of course, our office would reject any UCC filings if they were obviously a sovereign citizen (and sovereign citizens are usually not subtle), but some states don't do that.