Outlook 2003

Assume ComputerOne and ComputerTwo use the identical mail server.
I want to synch the email on both machines.
Say I delete all the email on ComputerTwo.
I export Outlook mail from ComputerOne and import it into Computer2.

After the import, ComputerTwo email should be in synch with ComputerOne.

However, when ComputerTwo goes to the mail server, it downloads duplicates
of what is already there.

Outlook does not seem to recognize that it already has a given email from
the mail server.

Is there a way to prevent duplicates from being downloaded?

Thanks