3TB External hard drive

So I bought a 3TB western digital external hard drive for my macbook pro and I am mainly using it for storing HD video that apparently takes up a lot of space. I have 750gb capacity on my computer which is almost full, and then 600gb remaining out of the 3TB on my external, and theres no way I could of taken up this much space. There must be doubles or something going on. When I right click on the hard drive it says 3TB capacity, 750GB free. So when I go inside the hard drive and click on the big folder called “wd.smartware.swstr” it says its 1.6TB… Is there an app or a way to clean up my hard drive so I can take doubles off and such? I use Final cut pro x. I don’t want to reset my hard drive because theres stuff on it that I need and can’t fit on my internal hard drive.

Thanks for the help.

Smartware wont delete files from the backup, if you delete a 5GB movie from the computer, Smartware wont delete the the same file from the my book, so eventually the backup size will be bigger than the files that you could have in the internal hard drive. You should have other folders aside from “wd.smartware.swstr”, that are also occupying space. 

Is there a way or an app that I can organize whats on my external hard drive? It says 1.4tb is on there but I can’t imagine I would have that much so there must be doubles…