find duplicates across multiple hard drives and keep only the latest edit for free

[JonnyFire]

Hello forum boards fellows, I'm looking for a solution that is clogging up my business archives vault
i actually have 4 usb external hard disk drives (+1 time machine only)
purchased along the time with multiple backups of folders, project folders, very large audiofiles
I'm sure that there's a good 50% of the data amount wich is redundant and now i need to free up about 500gb of space for a recent project.
the hard drives are:
- 256gb lacie design by f.porsche (USB 2.0 powered)
- 500bg Lacie (AC powered)
- 1TB Mediacom (AC powered) (!!this one is showing problems!!)
-1TB Intenso (USB 2.0 powered)

IS There any (possibly free) application which can scan all the hard drives simultaneously and shw the duplicates only so i can keep only the latest edit of each one and set some space free ?
or any script,whatever

thanks
Jonny

 

[JonnyFire]

An additional note about the file formats of them
- 256gb lacie design by f.porsche (USB 2.0 powered) ------->Mac OS Extended (Journaled)
- 500bg Lacie (AC powered) ------------>FAT 32
- 1TB Mediacom (AC powered) (!!this one is showing problems!!)-------> FAT32 + EXFAT
-1TB Intenso (USB 2.0 powered)-------->Mac OS Extended (Journaled)

I tried on the MacOS ones to run DiskinventoryX (http://www.derlien.com/ ) but it works with only one device at the time and doesn't show duplicates (files or folders)