Hmm, that use of qq smells bad. Of course without knowing the context I cannot say it's wrong... but it really, really looks like the coder wrote qq by accident, instead of qw.

Be that as it may, a reason why one would use qq and qw instead of "" and qw is on aesthetic grounds. It makes things line up more nicely. This in turn means less visual distractions, which lets the mind concentrate on other matters more important.

In other contexts, I have been known to quote strings with q() (that is, strings with no variable interpolation). Should interpolation later be required, the opening delimiter is changed from q() to qq(). This is a bit of win, since you don't have to chase down the end of the string to change ' to ", had you been using the ordinary '' delimiters.