Check comments for duplicate content using Google AJAX Search API as they are published. This helps to avoid having duplicate content in your posts. It only checks approved comments that have over 50 words. The plugin searches two random strings, both 8 words length. If one of them finds an exact match, it emails you letting you know so you can check it yourself and decide if you want to delete it.
- Download the plugin.
- Uncompress and upload to the folder wp-content/plugins/ (wp-content/plugins/no-duplicate-content-in-comments/).
- Activate the plugin.
- Go to Plugins > No Duplicate Content in Comments and enter your Google AJAX Search API for that blog (the link to get one is in that page too).