I must be an idiot - but help says "click on tools and select duplicate file finder." in my version of Opus 10 there is no such menu item, and i see no other possible location.
the alternative of course is that someone else is an idiot.
Robin
The Duplicate File Finder is only in the Pro version of Opus.
A summary of Light vs Pro features is here:
gpsoft.com.au/program/pro-lite.html
If you want to upgrade to Pro you can do so for just the price difference, via here:
gpsoft.com.au/DScripts/upgrade.asp