A backup is only as much worth as your restore capability. Backups created with BackHub can directly be restored and recovered back to GitHub.
When restoring a repository from one of your backups, BackHub is creating a new repository in your GitHub account, pushes the git repository and adds all issues, milestones and the like through the GitHub API.
Since BackHub is accessing GitHub through your GitHub account, issues are filed under your name with the current timestamp. This is a limitation of the GitHub API. However, the original author and timestamp of an issue is added as text in the first line of the issue description.
Related topics in the FAQ: