We have used the WordPress Duplicator Plugin many times to backup sites and move them to new hosting solutions.
However, on occasion we find special characters in pages and posts, such as Â or Ã. So here is a simple way to remove them.
Log onto your mySQL DB and check if you have any special chars:
SELECT * FROM 'wp_posts' where 'post_content' like '%Â%'
If you do, then use this simple UPDATE command to replace them:
UPDATE wp_posts SET post_content = REPLACE (post_content, 'Â', '');
Hope that helps.