Can I create more than one repository for github pages?

You can have one site published to https://<username>.github.io by publishing to the master branch of a repository named “username.github.io” (substituting your actual username).

You can also have an additional site per GitHub project published to https://<username>.github.io/<project>. Project settings let you choose which branch and directory to publish.

A better description is available in the GitHub Pages documentation, including options for using custom domain names.

(since April 2013, all username.github.com are now username.github.io)

You can only create one user or organization site for each GitHub account. Project sites, whether owned by an organization or a user account, are unlimited.

GitHub Pages sites

There are three types of GitHub Pages sites:
project, user, and organization. Project sites are connected to a specific project hosted on GitHub, such as a JavaScript library or a recipe collection. User and organization sites are connected to a specific GitHub account.

To publish a user site, you must create a repository owned by your user account that's named <user>.github.io. To publish an organization site, you must create a repository owned by an organization that's named <organization>.github.io. Unless you're using a custom domain, user and organization sites are available at http(s)://<username>.github.io or http(s)://<organization>.github.io.

The source files for a project site are stored in the same repository as their project. Unless you're using a custom domain, project sites are available at http(s)://<user>.github.io/<repository> or http(s)://<organization>.github.io/<repository>.

The publishing source for your GitHub Pages site is the branch and folder where the source files for your site are stored. If the default publishing source exists in your repository, GitHub Pages will automatically publish a site from that source. The default publishing source for user and organization sites is the root of the default branch for the repository. The default publishing source for project sites is the root of the gh-pages branch.

There is a possibility to host multiple pages within the same repository having sub-pages if you are fine with code duplication.

The latest version of my website is hosted on http://username.github.io/REPONAME This is a screenshot of the structure of my root repository where I host the latest version of my website:

Inside folder "2.4.0" I can host a previous version of the same page ,which is then reachable at: http://username.github.io/REPONAME/2.4.0 This is the structure of the folder 2.4.0:

Using this methodology of sub-pages within a main page, you can host multiple sub-pages within one main page.

No you are not limited, it is possible to have multiple GitHub Pages sites within one account. Create another GitHub repository and push your site files to the gh-pages branch. This would result in the site being hosted at tshepang.github.io/repo-name

Now, push another file "CNAME" to the same repository and branch and fill it with movies.tshepang.net. Log in to your DNS host and add the CNAME to point to "tshepang.github.io" (just like the original site).

This would allow you to have seemingly two different sites on different domains. This would not work for having two or more sub-domains within github.io itself.