I'm on a Macbook Pro and I was using the trackpad. I hooked in my PC mouse to test and the problems are the same: duplicate creation and inability to delete. Also of note: I experimented further and even images that are not created on frame one usually refuse to delete. I'm not sure what it was about that original image that allowed me to delete it, but it was not the delayed creation.
I'm going on vacation, but when I return I'll try reinstalling just in case I've got a corrupted file causing these issues or something.