Os problemas de conteúdo duplicado resolvem-se com a introdução de código apropriado em .htaccess file,
Implementing 301 redirects for an Apache server:
Step 1: To implement a 301 redirect the file we need to work with is the .htaccess file. To access the file you need to go into your FTP and look into the document root.
Step 2: If you can’t see it, enable viewing of hidden files since the .htacess file is hidden. If there is still no .htaccess file present , create one with a simple text editor.
Step 3: Insert this code in the file:
Code example from non www to www:
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC]
RewriteRule .? http://www.example.com%{REQUEST_URI} [R=301,L]
Obviously you will need to replace ‘example’ with your own domain name.
Also make sure the Rewrite Engine is turned on, you will just need to turn it on once.
Step 4: Save and Test it!
Já agora, atenção à segurança, uma vez que o assunto é wp, a minha sugestão é o plugin Better WP Security, back up a base de dados antes da instalação, ler com atenção as instruções e não renomear ficheiros.