Duplicates app scans for multiple copies of digital files that you might not have realized were wasting your storage space and compiles a list of them. On devices used to store many large files, like digital copies of movies or television show episodes, accidental duplicates can potentially waste several gigabytes of storage space.
You can use the app to scan the Android device it's installed on. Also, you can input a TXT format file that contains a Windows device's volume listing to run a check for potential duplicate files on that device. These are obtained by pressing Win+R on the Windows device, typing "cmd.exe" into the Run prompt, then navigating to the root folder of the volume you want to check and executing the command "dir /s > files-list.txt". It may take some time for that device to finish writing the volume listing to the text file. When it's done, you can move that TXT file to your Android device to use Duplicates app to analyze that volume listing.
You can export the compiled list of potential duplicate files to a TXT format file which you can then print or covert to a spreadsheet for easier reference.
For your data security, Duplicates app does not open any of the files on your device to do a bitwise comparison. It simply compiles its list of potential duplicates based purely on file size. The user must then review the list to determine if the files of identical file size are in fact duplicates or not. The app does not store any of the information it gathers about the files on your devices in any permanent way and that information is not transmitted off of your device by the app or sold to anyone.
For similar reasons, Duplicates app does not have the capability to delete any of the duplicate files it finds. This must be done by the user.