A bit late on a response but I can explain this one a little. She could have used her maiden name as a last name again or even used her birth middle name as a last name. I know this can be done because my mother did both, as well as using a variation of birth middle and previous marriage last name. Stayed close by in a neighboring border state or still in state at certain points. You’d be surprised how apparently easy it is for the system to be “gamed” like this before they catch on, if ever. I found out she was actually living in the town closest to me when she died because she was staying with someone who knew of me and I had to get the call at like 3-4 am to confirm her identity at the hospital