Sometimes I will start looking into a subject, and I will start collecting pictures. If you find a web site that has several pictures you want, I find it is quicker to simply save the entire web page than to download each individual picture. Maybe it's just my browser, I don't know.
In any case if you do this from more than one site, you are liable to find you end up with multiple copies of the same picture. People steal pictures ruthlessly. To get rid of the duplicates, you can use two picture viewing programs, and resize the windows to share the screen and visually compare them. That can be a bit of a pain. I normally run all my Windows programs at full screen resolution. Dealing with windows that are smaller than that is a pain.
There are programs that will locate and delete duplicate files for you, but they generally cost money. I wrote one many moons ago, and it still works, but it runs in a DOS box and is slower than molasses compare to some of the new ones. If you are only looking at a few files, or you can let it run, it's fine.
The programs to delete duplicate files won't necessarily work well for images, because the same image can be encoded in different ways. You can encode the same image two different ways and the files will be completely different.
I found a free program that looks for duplicate images, shows them to you and then lets you choose which one to delete. It's a little old, and it's a little clunky, but it's free and it works fine. It's call Dup Detector and it's available from Prismatic Software via RAREWARE here.
3 hours ago