A little-known feature of macOS is the ability to merge two folders with the same name, as long as those folders contain different files. So let’s say, for example, that I’ve got one item—creatively dubbed “Test Folder”—sitting on my Desktop.
And in my Dropbox, I have another folder with the exact same name.
Of course, if I just drag the Dropbox “Test Folder” to my Desktop, macOS will ask me if I’d like to replace the one there.
Here’s the “merge” part, though—if I instead hold down the Option key as I drag the first folder to the location of the second folder (not on top of the second folder), I’ll get a new choice!
If I pick “Merge” from that dialog box, macOS will do just that—it’ll combine the contents of the two folders. My Desktop version of “Test Folder” originally contained just a Pages file, but after doing this, it now has the two items from the Dropbox folder, as well.
Note that copies of those files still live in my Dropbox; this doesn’t delete the originals. That said, “Merge” doesn’t provide an “Undo” option, so…yeah…if you’re concerned about your files, please make sure your backups are solid before you use this. Just in case.
Now, while this feature is very cool, it’s also incredibly persnickety in my experience. As Apple notes in their support documentation:
The Merge option appears only if one of the folders contains items that are not in the other folder. If the folders contain different versions of identically named files, the only options are Stop or Replace.
So as you can see, you might get this dialog box instead of the “Merge” one pictured above if you’re trying to use this feature with folders containing different versions of the same files:
I mean, I guess this is a good safety net to prevent you from overwriting important versions of things! But at least there is a way to clean up some of the identical folders on your Mac. I know I personally have around twelve different folders labeled “2016,” for example, in various places on my computer. If Spotlight didn’t make it so easy to find things without having to be all neat about it, I’d probably be panicking right now.