Apps / Software :: Exporting / Importing Of Outlook 2010 Email Accounts?

I recently had to update a second computer's emails from another computer, both having Windows 8.1 and Office Professional--or sync them. So I exported all three .pst accounts in Outlook 2010 from computer 1 and imported all of them into computer 2 into Outlook 2010. Well, I didn't notice that there was a Duplicate setting (probably because I don't normally do this) and left the Import setting concerning duplicates at the default setting, so I got a lot of duplicates. Since then, I have received more emails into my accounts at computer 2. What is the best way to fix the duplicate issue?

Also, I noticed that many Sent folders were missing in one Imported account for some reason. Why would just some of the emails be Imported and not others? This is bad! If it wasn't for this, I could send an important email today. How can I make sure that all of the emails on computer 1 get Imported onto Computer 2? All too often, I find glitches in MS software.