Unfortunately, I did not find this exploit like all my others... ..... but, it's a good exploit.
Now, what you do is:
1. Kill a mob and don't loot it.
2. Pull another to the same place but don't attack it.
3. Move so that you can see the dead and live ones on top of each other.
4. Shift-click the dead one to start auto-looting but then quickly hit "tab" followed by "1" to start attacking the live one.
I prefer making a macro, or something in Autoit....
Here are screenshots from 4 different people from a different forum: