Really fascinating question, I felt compelled to look into it to find out!
I'd say there are 3 possible answers to this:
The most likely answer: Pentax engraved the first owners name (Masaaki Nakagawa in this case) on the camera before shipping it to them.
Evidence suggests that Pentax would sometimes engrave the owners name on a new camera before shipping ...
This article explicitly discusses the differences between the 2. Whether or not those differences are worth any variation in price is entirely up to you.
Enter the K-1 Mark II, a new DSLR which is almost identical to its predecessor, but with the inclusion of several new elements: