The information being shown is based on timezones. Some members viewing a profile will see the same dates on both, others will see what's in the screenshots.
Here's the actual data on the first account.
"last_online": 1193999325 -- GMT: Friday, November 2, 2007 10:28:45 AM
"joined": 1193999113 -- GMT: Friday, November 2, 2007 10:25:13 AM
It's possible that the code isn't applying the viewer's timezone correct for both values, giving the discrepancy on some instances. I know staff are aware that it happens on occasion.
Um...okay. Well, I might research this info a bit more then.