|Addressing a "New" installation and Outlook profile, If your current Outlook configuration is set to leave the messages on the server and not delete them after a specific time period (or if emptied from the Deleted items,) then they will indeed download again.|
You'd have to change the account configuration to say Leave messages on the server and remove after 1 day. Then, download your messages and don't configure the new Outlook until 24 hours later.
However....since you say all you're doing is reinstalling Outlook, then you in theory won't be creating a new Outlook profile. So the configuration for leaving messages on the server will not result in the messages being downloaded again.
Just out of curiosity, why do you need to reinstall Outlook?