The resemblance is not coincidental. An old college buddy of mine is a naval architect who was part of a staff of designers that were working on the DD-21 design. They were looking for a design that was stealthy, stable in rough seas (i.e. low center of gravity), and able to carry a significant payload. They studied all kinds of ships, but after looking at the old ironclads realized just how far ahead of their time they were. I won't say that they set out to copy the design, but they added the 20th/21st century improvements, and came up with this design.
Funny how the more things change, the more they remain the same.
The War of Northern Aggression (sorry yanks, but it's true) gave us a great many improvements in the art of war, many of which are still in use in one form or another to this day.
You want a real surprise, go look up the original design of the Stealth Bomber.
Nazi Germany.
The prototype is in the Smithsonian Air-and-Space.