Triplet Brothers

       
There are 3 triplet brothers. They look identical. The oldest is John, he always tells the truth. The second is Jack, he always tells a lie. The third is Joe, he either tells the truth or a lie.

Jimmie Dean went to visit them one day. He was wondering who was who. So he asked each person a question.

He asked the one who was sitting on the left: "Who is the guy sitting in the middle?". The answer was "He is John."
He asked the one who was sitting in the middle: "What is your name?". The answer was "I am Joe."
He asked the one who was sitting on the right: "What is the guy sitting in the middle?". The answer was "He is Jack."

Jimmie Dean got really confused. Basically, he asked 3 same questions, but he got 3 different answers. Would you find out who is who for Jimmie?