This method of identifying visitors across devices is no longer recommended. Please refer to the Adobe Experience Cloud Device Co-op Documentation .
Geo-segmentation data is recorded based on the first hit of the visit, and does not change for a single visit regardless of the device used.
If a customer browses your site from his or her home computer, and then from a mobile device within 30 minutes, the geo-segmentation data is not changed. If you are using VISTA to populate an eVar with geo-segmentation data, it is based on the IP address in each hit. This could result in multiple geo-segmentation data values if the IP address changes for the same visit.