Find duplicates where ever they are what ever name they have. Chipmunk considers strictly content. No mucking about with creation dates and file names and stuff. You will be amazed how quickly Chipmunk eats through hundreds of megabytes, considering it compares the content of these files.

If you can access it you can search it. External drives, network shares, removable media, you name it. Delete all files in a folder that have duplicates elsewhere. Or vice versa: Delete all files outside a folder that have duplicates inside it. Or hand pick your candidates, of course.