I use Duplicate Cleaner for this and many other things. It can find all files not duplicated between locations, by setting it to scan for duplicates between (not within) two locations, then using the list of everything that wasn't found duplicated. Source: over 1 year ago
Do you know an article comparing Duplicates Cleaner to other products?
Suggest a link to a post with product alternatives.
This is an informative page about Duplicates Cleaner. You can review and discuss the product here. The primary details have not been verified within the last quarter, and they might be outdated. If you think we are missing something, please use the means on this page to comment or suggest changes. All reviews and comments are highly encouranged and appreciated as they help everyone in the community to make an informed choice. Please always be kind and objective when evaluating a product and sharing your opinion.