How to avoid duplicate Url for the home page

From the comments:

What are your settings under Dashboard -> Settings -> Reading. Specifically, what are your Front Page Displays, front page, and posts page settings?

And your reply:

exactly this is the point, the client has used a Theme called Choice and in the Theme Frontpage Settings there is this page selected :”Welcome to your best Summer”. In the menu bar drop down with the option i can choose whatever page i want.

This is the problem.

WordPress provides settings for using a static page as the site front page. Use them, instead of custom Theme options for the same purpose. If the core WordPress Front Page settings are used, WordPress will automatically redirect the static page permalink to the site front page.

So, to fix:

  1. Go to Dashboard -> Settings -> Reading
  2. Set Front Page Displays to a static page
  3. Set the page on front setting to Welcome to Your Best Summer
  4. If you need a blog posts index, choose a static page to display it, via page for posts
  5. Then, most importantly, if the custom Theme option interferes with the core handling of the Site Front Page, you may need to clear out that custom Theme option.