How are double question marks used in a sentence?
For example a question "Are you kidding??" would emphasise that there is something wrong with the question; in that it is asking something which is impossible, outrageous or is maybe a question which is stating the obvious.
Double question marks are never usually used in poems, newspapers, texts etc as using double question marks isn't punctually correct.
If double question marks are uses it is to emphasise something in return, usually from the shock of the previous thing said.
For example, if I said:
'My dog just died' (sad, but used for example...)
Someone may reply
As the dog was a puppy and the death was unexpected.