It is a coincidence but it's a good way to remember which is port (left) and which is starboard.

The actual origin of the term "port" is speculated to be because the left side of old merchant sailing ships had a loading or entry port. The right side had a steering board that hung over the side of the ship (before the invention of rudders) which is where the term starboard comes from. So if the steering board hung over the right side, the boat would need to dock on its left side, or put into port on its left side.