How can I avoid creating duplicate prospects in Pardot? I'm seeing multiple contacts with duplicates being added. Is there a way to catch them before they're added officially? 

It's frustrating because I created a segmentation list targeted to send an email. But then some people who were not supposed to get the email got it because of duplicate prospects. How can we avoid this situation?  

I need to find a way to prevent duplicate prospects being created.

Any help would be greatly appreciated.