Ah. That's probably just an error. The same page should load at http://brandname.com/folder/article1/article2.

I would remove the extra /, update all the links to the pages and set the proper canonicals.

Double slashes means that if you are on a https page, the links will be https. On http pages, links will be http. Its most commonly used when you have a sitewide include and want some pages to be https compliant without sourcing the https on http pages.

As long as there isn't a https AND http version of the same pages, you should be fine.

Try this. It uses the web.config file which is accessible via FTP.

Well there ya have it. DA is mostly based off the authority and quantity of a sites backlinks.

No backlinks? Blocking crawler?

Ah, in that case the main factor is: how are all ranking currently? If they each receive traffic for their respective local keywords, it would make sense to just keep them as is (don't fix what ain't broken).

However, if you feel they aren't getting the rankings they deserve, you should combine all the sites into 1 and consolidate the authority. As long as you set up 301 redirects correctly, you should be able to transfer your rankings and even improve them (if you set up your internal linking structure correctly). Just know you will most likely lose rankings for around 2 weeks.

Something to keep in mind: it's much easier to maintain and improve one website over three. If you plan on generating new content (as you should), having 1 blog with kickass content is far better than 3 mediocre ones.

Best,
Oleg

Are they all related? SEO aside, would it make sense to combine them all?

If they are all similar and target similar keywords, it may make sense to combine them all and consolidate the authority. Tough to judge without knowing more info.

If you like, you can PM me the links and I can take a look and give a better suggestion.

Cheers,
Oleg