Importing leads from a report into a campaign

Importing leads from a report into a campaign

I have a report that lists leads based on certain criteria and what I need to do, is to move the listed leads into a campaign.  I thought the best way to do this would be to export the report results to CSV, create the campaign and then import the leads from the CSV into the campaign. The only concern I have is that it asks if I want to overwrite/skip/clone, but I am unsure what to select because I don't want affect any existing lead records.

Please advise the best way to get the leads in the report into a campaign?

Thanks for your help!