Does the import option in dashboard ignore duplicates?

I’m in the process of transferring a site to a new host. The database was huge, so it took a lot of effort to get it restored on the new host. The problem now is that the ‘new’ database is now 3 days old, so I’m out hundreds of posts and comments. I noticed the export option in the dashboard. It exports options are by month. I need three days. If I select a month and run the import via the dashboard on the ‘new’ site, will it ignore duplicate records, overwrite them, or crash and burn?