How to resolve http vs https duplicate content issues

For Google there is no difference for http or https. You should do redirect from http to https and keep https only.
After some time, when indexing will be done, in search you should see https links only. Google Analytics will be updated with new data too.

Hello,

Before I answer your question, please allow me to throw at you a couple of things about http vs https:

-HTTPS ranks better than HTTP in search engines mobile/desktop.
-HTTPS gets less value from monetization compared to HTTP.

Now coming to your question:

1- Move from HTTP to HTTPS

I would highly recommend completely switching to HTTPS if your company website does not monetize or make much money from AdSense. And to achieve that there is always 3 steps to move your website from HTTP to HTTPS.

Step 1: Redirect seo 301 http to https by editing your .htaccess file as follow:

Step 2: Make sure that your website and web pages source code contains a canonical tag is pointing to https NOT http example of a homepage:
Step 3: Login to your webmaster tools and add a new website but make sure to use https://youwebsite.com. After you have done that, in the same webmaster tools console find your old website as HTTP http://yourwebsite.com and then use the change address tool to move http address to https: https://support.google.com/webmaster...er/83106?hl=en
(it takes a maximum of 180 days for your website to completely transfer link juice from http to https and essentially crawled properly.

Done.

2- Move from HTTPS to HTTP

On the other hand, if your website is monetizing ads from Adsense. Then you should stick with HTTP until HTTPS is fully supported and optimized by Adsense. To accomplish this task you have only two steps:

Step 1: redirect seo 301 https to http by using the following code:

Step 2: Make sure your canonical tag is pointing to HTTP. Example of a homepage:
3- Keep both HTTP and HTTPS

There are many websites using both protocol versions. But the canonical tag should point to your preferred protocol. And another common issue with some users is that they use links like this <a href="/contact.php"> instead of the proper way which is <a href="http://yourwebsite.com/contact.php"> so make sure your links and images or other media files are linked using your preferred protocol. Applying these changes should prevent search engines from crawling unwanted protocol and hence duplicated content.

That's pretty much it!