As you know, the file samples.zip contains several projects covering all tutorial steps.
When you try to import from such a file, Tersus (or rather eclipse behind the scenes), checks whether your workspace contains any projects which match (by name) the ones in the import file, and hides any it finds from the list of projects you can import (and displays a matching warning).
In your specific case, the repository explorer in the background shows that a project Tutorial 13-14 already exists, and therefore hides it from the list.
Of course you can re-import it, by deleting the existing project from the workspace.
For best results, use the Firefox browser..