Duplicate File Finder
Full user review
""Teaseware" - many features disabled in Free Edition"
Fast - compares actual contents
Numerous features disabled in Free Edition - each of them pops individually rather than being shown in a a "get this in the Pro Edition" list.
It's not clear if the "protected folders" feature would let me compare "archived" folders against a "base" folder, only finding duplicates between folders rather than within the "base" folder.
I'll probably un-install it within 30 minutes of downloading.