WS.Reputation

I am a software developer.  Two computers in our office have the exact same Norton Anti-Virus software with the exact same settings running on each.  These two computers are not connected in any way. 

 

I wonder why it is that when each of these two computers download the same software from the same internet location,  a False Postive for WS.Reputation occurs on one computer - resulting with its immediate removal,  while nothing at all occurs on the second computer - allowing full installation of the software without incident. 

 

Tony