Where is the 2nd JN 055 fitting out / docked? When I was in Shanghai two weeks ago, I saw a ship docked on the Huangpu river that resembled a 055. It was very far away, so I could not tell for sure what type of ship it was, but the overall shape greatly resembled the 055 (mainly, the line that starts from the bow, sloping down on one side and sloping up on the other). There really is no other ship that I could think of that shares the same shape.
I believe you saw a Type 071. A Type 071 has a line similar to what you described. The shipyard in the Huangpu river pumps them out, and might be a new one that is on fitting.