I am an Analyst at Viacom and I am working on a project looking at user behavior on our app tagged with Adobe Analytics. What I see in the data is that sometimes, 1 visitor ID is counted as 2 Unique Visitors on the same day, on the same device. I am trying to find out how can this be possible? Any help is appreciated.
You must have captured Visitor ID into some evar/prop. So treat the visitor ID captured as a value for evar/prop. As Adobe identified visitor based on cookie (s_vi() or MID()). So 2 Unique visitor for same Visitor ID means, same value for evar/prop(captured as visitor id), 2 cookie got set.
This can happen if evar has a persistance whereas cookie set if image request cannot find related cookie(s_vi() or MID) on thebrowser.