Did you move your website or web page? Did you decide on a better URL for your blog post? then use 301 redirect! 301 Redirect is a like an address change announced on the google newspaper so that the public and google knows where to direct your traffic!
Say you started with my-awesome-bloooooog.com and you were so successful, and you became known by the nickname mab000g and acquired the domain mab000g.com then you can do a 301 redirect on your old domains o that google knows you have moved!
Maybe you wrote a blog post on WordPress and it's url is blah blah blah /great-dau-on-the-beach. Oops there's a typo, the web page should be /great-day-on-the-beach. Use Wordpress's admin panel build-in 301 redirect.
If you redirect all duplicated pages, channel their all traffic into one canonical webpage, Google's smart algorithm will weigh this page the most and give it the most ranking and traffic, ignoring others as duplicates. This way Google also won't publish you for having too many duplicated contents, and thus avoid the risk of appearing to game the system.
This is a server side modification. Th .htaccess file in Apache server can be modified to govern 301 redirects. PHP developers can use .htaccess file in LAMP WAMP MAMP stacks to make changes. wp-admin of Wordpress has a graphical easy-to-use interface for managing 301 redirects.