If you are running the same PC for a number of years you will eventually notice an increase in duplicate files on the system. This is especially the case if you like to download files in bulk from the Internet, for instance big image archives or music archives. While you can sort the collection manually it may have grown to a size that you can't manage manually anymore. Comparing all images of a collection of 50,000 or more images is something that would take a long time.
Software like Noclone automates the process, and while the free version is limited in the number of files it can check in one go, it is an efficient and fast program that you can use for that purpose.
All versions of the program use the same setup file which can be confusing at first. Just download the program to your system and select free edition during setup. The program opens the search configuration on start. Here you can select some, but not all options as some are limited to the commercial versions of the application.
The features enabled in the free version are scanning a folder and all of its subfolders for duplicate files, duplicate mp3s, similar files or duplicate Outlook emails. The options to compare folders and to find similar images are not available in the free version.
Once you have made that selection and picked a root folder, you can click on the search button to start the scan. Depending on the data set and performance of the PC, it may take a while to complete. The similar files option for instance takes a lot longer to complete than the exact duplicate files or duplicate mp3 scan.
It switches to the results tab automatically when the scan is finished. Here you find listed all duplicate files including their location on the drive, file names, sizes, and modification dates.
You now need to mark files that you want to remove. You can't use the Smart Marker option as it is limited to commercial versions. While it may take a while to pick all the files for deletion, it is still faster than comparing the files manually on your system.
The program displays notifications about the free version on exit and start of the program. It in addition highlights that before scans, and when you try to use a program feature that is limited to a paid version. That's certainly overkill and bound to drive many users away from the program. If you do not mind that, for instance because you intend to run it once every couple of months or so, you will come to the conclusion that it is a fast efficient duplicate file finder for Windows.
I'm also not entirely sure if there is a need to register an account after 30 days as this seems to be indicated by the start and exit popup.