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Yes, Wordpress SEO is the Yoast plugin: https://wordpress.org/plugins/wordpress-seo/

Let me try and tackle these one by one: Capitalization: Yes - typically you can handle this with a server-level redirect that forces all URLs to be lower case. Google will see the upper case version as a separate page, and that's why it's getting flagged as duplicate content. Be sure to double check that this is being process as a 301 and not a 302. Wheregoes.com is an easy quick way to check. 5 Sleep Options: I'm not sure why, but http://www.bellybelly.com.au/5-sleep-options-for-your-baby-where-will-your-baby-sleep is producing a list of articles almost identical to the ones being shown at /birth. So, that's the cause for the duplicate content here. I'm guessing it's a CMS error of some kind. f196 vs f193: These are showing as duplicate because there's nothing unique on the page except for Queensland vs Victoria. You'll need to find a way to highlight threads that are about Queensland or about Victoria to make this page useful, or you can simply "noindex, follow" these pages so that the duplicate content is irrelevant. /tas/doulas vs tas/etc., etc. These are duplicate content because they all say "No advertisers found matching your criteria." That's it. They need to have some real actual content, otherwise there's no reason for them to exist. For these directory listings, try creating a bunch of free listings to serve as temporary filler and it will also encourage other competitors that they should consider doing a listing as well.