In the past, I downloaded the macOS Sierra installer onto my old MacBook. And a couple of months after this, I ran CCC and it said that files related to this installer were corrupt. So I deleted this file from my old MacBook. Today, I was going to download a clean copy of the macOS Sierra installer onto my newer Retina. However when I did this, I got a pop-up saying it wanted to *install* Sierra. After some searching, I discovered that I had a "Install macOS Sierra.app" (5.03 GB) filed away somewhere on my Retina. Clearly not remember where things were at or what I had done in the past, I'm a little afraid that this second copy could be corrupt too, and I'd hate to want to re-install Sierra down the road only to find my copy is bad and that I can no longer get it off of Apple's website. Short of downloading the 5GB file again, is there an easy way to verify if this 2nd copy on my Retina is in working order??