Duplicate meta descriptions in category directories

Hi, everyone, this is driving me nuts. I have a protein powder website with around 10 articles dealing with various powders, protein, etc.

https://www.bestproteinpowderhq.com

Each article has its own unique meta description. However, various articles are lumped together in “Blog archives” section (under the /category directory). For example:

https://www.bestproteinpowderhq.com/category/beef-protein/

Google Webmaster Tools shows that I have a bunch of “duplicate meta descriptions” under each category since each category has several articles and within those articles are the original meta descriptions. So GWT says I have duplicate meta descriptions:

Find all the pros and cons of dairy free protein powder supplements here. Great source of lactose fr
/category/beef-protein/
/category/egg-protein/
/category/rice-pea-protein/
/dairy-free-protein-powders/

I’ve already had robots.txt disallow the entire category directory:

User-agent: *
Disallow: /category/
Disallow: /tag/
Disallow: /author/admin/

I even had GWT remove the URLs, yet with each Update, GWT keeps on telling me I have duplicate meta descriptions.

How do I either get GWT to not see this category directory or somehow remove the meta tags from the “bog archives” category archives? Thanks.