Duplicate ghost files

I just noticed something while sorting photos around in some folders. I'd click one, and suddenly another picture file appears to get created right under it with the exact same filename & extension.

I tried to delete the duplicate thinking I accidentally hit "duplicate" instead of "copy" when right clicking, and the Original file was also sent to trash. I pulled it back out and it did it again. When I moved it into the subfolder, the duplicate vanished.



Anyone else experience this strange behavior? It doesn't appear to be a serious issue, as it's been fixed since the reboot. I just wonder what was going on..