Really strange URL's being indexed

Hey there-
I've been swimming in google crawl errors & duplicate title and description tags for the past few weeks. While crawl errors are very slowly decreasing (and new ones popping up), duplicate title and description tags are increasing.

Here is an example of a strange URL being crawled:
http://tutuology.com/page/2/?cat=5
This actually leads to a page which I have attached below but it is linked to a page that doesn't exist:
http://tutuology.com/category/buy-my-ebook/page/2/

Also, regarding the duplicate problem, please see the screenshot below of the problem.
Any guidance would be much appreciated :slight_smile: