It's free, so it can't be any good. The maxim that you get in life what you pay for generally applies, and similarly here, if it's free, then chances are it's going to have some side effect years later, like some drug from the seventies.
It's just another example duplicate photos finder of Big Brother society. The duplicate file finder freeware, on the pretext of checking your computer for duplicate files, is actually busy obtaining all the information it needs to be able to market to you a new mobile phone tariff.
Why the duplicate file can't they just create one program that does all of this for you, instead of creating lots of piddly little programs.