I am just wondering is there any way to find out duplicate files in my MAC? Because when i download something from "torrent", some unnecessary file also download besides the main file with .dat extension. I want to delete all of these .dat extension files at a time. Because it's a lot of in numbers & store in many different directories. If i want to find them one by one i have to do a lot of works. Is there any free apps to do that job or some way i can find & delete them? If you know please share with me.
Thanks in advance.
Have a nice day.

I am using "MacBook Pro" with OS "Mavricks".