Is this considered duplicate content?

[Quick]

Hey guys I hope someone can point me in the right direction here. I'll try to explain my situation the best I can.

Let's say I have a category on my site.

And this category has 2 sub-categories:
Sub-Category A
Sub-Category B

Some posts are only relevant to Sub-category A and some only to Sub-category B so these get tagged appropriately.

But other times I have a post that's relevant to both sub-categories

If I tag these posts as belonging to both A and B so they show up under both sections of the site is this seen as "duplicate content" by search engines?

The actual URL for the post is still the same (it doesn't feature a category)

Ex. mysite.com/post-title

Instead of... mysite.com/category/post-title

Anyone have an idea whether this would be an issue?

Should I consider no-indexing the category pages?

 

[Ryuzaki]

I usually noindex anything past page 1 of a paginated category page for this reason (but keep it dofollow). I only categorize posts in one category for this reason, as well. It's not a problem I think if you don't have 20 categories or tags with the same posts in them, but it was something Panda looked at (duplicate content like descriptions and post titles across tons of category pages).

 

[JasonSc]

Maybe I'm missing something, but the concern is if the post appears on both tag pages?
Doesn't the canonicalized address this issue?

Sorry this is more of a question then an answer.

 

[GeorgeG]

The blog post should be excerpts from the original article with a link to the article itself. This excerpt being in 2 different categories is not a duplicate content.

That being said, you should make your category and tag pages robots to be - noindex, follow
This is to avoid too many pages with thin content that contain only links to other post be indexed in the SERP.

If you use WordPress, the most common SEO plugins like Yoast can handle this for you.