My friend recently gave me a used drive, and at the moment I have a 500gb wd blue. The drive my friend gave me was a 500gb wd green. I was originally going to use the hard drive to backup my blue (I dont have a backup). But I started thinking, what would be better? To use the extra 500gb to backup my 500 gb blue? Or use the drive normally and have a total of 1 tb? Which would you do?