A moment later. That sounds to me like you might have some kind of a syncing issue. Is this in a folder that is synced with some syncing service?
If one of the above answers solved the problem, cool. But I suspect there may be something else going on.
By default, when you drag, you should have:
- your original image in your original folder, and
- the new attached image in your attachments folder.
But it sounds like you are saying you end up with 3 images:
- Your original image
- your new attachment, and
- a new copy of the attachment with a different name.
Is that right? Because that would mean you still have a strange issue happening.