In the past few years, we have covered plenty of SEO plugins that can help you get your focus keywords, kw density, and titles right. WP Merge + Similar Finder can help you take your SEO campaign to the next level. It allows you to merge posts to avoid duplicate or very similar content.
For starter, this plugin can analyze your posts to find the ones that are very similar. It lets you define merge order and exclude common words. You can set your merged posts to have all the attributes and properties of the original articles. WP Merge + Similar Finder is WPML ready.
Asasi is the developer behind this interesting plugin. You can find out more about it on CodeCanyon.