Duplicate Results on Google Search

Well, i created a new site 2 weeks ago, and the pages started getting indexed, but the problem is that each page is getting indexed twice. I really don't know what to do to fix it. This happened after i added "www." from my wordpress admin panel.

After doing that, when i search for site:www.mysite.com, it only shows the new articles which were posted after the www, and with site:mysite.com shows all + duplicates. When i click on results with no www, it redirects to www.

On Google WMT i chose show the www version, but when i registered it there i did it without the www.

Some people tell me that it should get fixed soon since i added www in wordpress panel, but i am still not sure what to do.

Any help is appreciated

Set your canonical URL and make sure you are being consistent with URL formats in navigation links, sitemaps, RSS feeds, and configured redirects...
Double check your preferred domain and HTTPS setting in GSC as well.

If you are not very strict about URL formats you will confuse the shit out of Google and it can take weeks for Google to clean it all up once you get it all in order.

You will need to setup Canonical for all your pages, also, setup a 301 redirect from www to non www or vice versa as you perfer. Also, make sure to do the same for http and https connection.