If you'd like to keep your Help Center private from search engines, you can disable search engine indexing on your Help Center, which will prevent your articles and collections from appearing in Google search results.
Disable search engine indexing
Go to your help center settings (Settings > General), you have the “Search engine indexing” option, you just have to deactivate it and press the “Save changes” button. That's all!
This will allow you to share your articles only internally or host article content elsewhere without SEO duplication.