Clean URL leads to duplicate URL after migration to another hosting
To correctly enable/configure Clean URLs, refer to Configure Clean URLs in the installation guide.

If you're not familiar with Clean URLs yet, I suggest to review that documentation in the installation guide carefully (for the version of Drupal that you're using) and make sure your server is correctly configured before proceeding.

Here is a summary of common steps/issues:


With Apache HTTPD as web-server, you have to enable mod_rewrite and configure the necessary rewrite rules in the .htaccess file.
Usually, theses rules are applied automatically, when mod_rewrite is enabled. But in some cases, the AllowOverride directive is too restrictive to allow this.