I have two dates that are identical and it's being logged as a difference. I inspect the objects and they are exactly the same
DifferencesString " Begin Differences (1 differences): Types [DateTime,DateTime], Item Expected.LastUpdate != Actual.LastUpdate, Values (10/2/2014 12:38:18 PM,10/2/2014 12:38:18 PM) End Differences (Maximum of 20 differences shown)." String
Above is the output of the differenceString..