Indeed.com uses the double hyphen in their URL scheme and it certainly doesn't seem to hurt them.  I Imagine this is due to being able to reconstitute this back from URL rewriting so they know the difference between a dash in the URL that replaces a "space" vs a -- which would reconstitute back to a dash.

Example:q-Tennis-Channel-jobs.html

Maps back to the company Tennis Channel

Example: /cmp/Sag--aftra

Maps back to the company Sag-Aftra