Why is Moz Crawl Diagnostics labelling pages as duplicate when they appear to be different?

[A_Q]

Moz Crawl Diagnostics is flagging some pages on the Doorfit website as duplicate, yet the page content is completely different and not identical.

Example.

Page: http://www.doorfit.co.uk/locks-security/secondary-security

Duplicate: http://www.doorfit.co.uk/seals-and-sealants?cat=279

Does anybody have any suggestions as to why this might be the case?

Thanks

[MonicaOConnor]

I would add some content to these pages. When you look at the source code of those pages the html coding is almost identical. That is most likely what is causing the duplicate content error. There is no text to html ratio, it is all html coding.

[A_Q]

Thanks for the answer!

Do you think this might be the case for this example as well?

Page : http://www.doorfit.co.uk/shelves-and-storage?cat=275

Duplicate: http://www.doorfit.co.uk/shelves-and-storage/tube-rails-and-fittings/18133-25mm-chrome-end-socket-c-w-grub-screw

[MonicaOConnor]

I think that it is a good possibility. I wouldn't put Canonical tags on the product page however. The product page isn't the same as the category page, the html coding is just very similar between the two.