For some reason it is now called DisK Analyzer however be very, VERY,careful if you use it.
It now finds ALL duplicate files by default, there are no filters to the scan.
It also has a ‘Batch Select’ that allows you to select duplicates en-mass for deletion.
The combination of those two things means that with just a couple of unthinking clicks you can easily and quickly delete hundreds of NEEDED System File duplicates.
Which in turn means that your computer and apps will stop working properly.
YOU HAVE BEEN WARNED!
If you have been careless and deleted all your needed System File duplicates then see this for how to go about repairing things, note that in this linked case the original poster took a different option and resorted to re-installing Windows rather than trying to repair it.