This question was posed to me and I did some Google reason and came up empty, so I'm hoping someone here can help. When opening an email that has an attachment, say a jpeg picture, 2 copies are apparently always placed in the Temporary Internet files location in Content.Outlook. One is the base file and the second is a copy with (2) before the extension name. This seems to happen on both 2010 and 2013 Outlook, and with different antivirus products on different machines. As best I can tell this always happens. Those attachments stay in the temporary folder too unless the actual email is deleted so over time Content.Outlook grows. Not that any of this is a major problem, but why are 2 copies always created when opening an attachment?