Yes they can mean near enough the same thing sometimes. But the first phrase is more like you expect it to be done soon -- it might be followed by "Well, hurry up then!". And the second phrase is more like you're shocked that it's done so soon -- it might be followed by "Wow! That was quick!"

#2 is a rhetorical question. The person has seen the completed task, and expresses surprise at it's (presumably) early completion. This question does not need an answer. #1 is a question seeking confirmation and the person asking does not know whether it is done or not.