I love this kind of stuff. James Reasoner stumbles onto an obscure private eye series , featuring the adventures of Mark Wonder, written by one writer but under two different names. 
Author Warren Murphy sort of did the opposite… he wrote two book series featuring the same insurance investigator and his Asian girlfriend but gave the characters different names. One series was called DIGGER, the other was called TRACE, and they both became the basis for the TV series MURPHY’S LAW, starring George Segal, which was my first staff job.
UPDATE (7-18-2005) James Reasoner’sliterary investigation into private eye Mark Wonder continues with another twist. This time the author is the same (Eric Thomas again) only now it’s the PI whose name changes. In STRIP FOR MURDER, Mark Wonder becomes Christopher Sly. 
I love Warren Murphy’s books. He’s one of the true underrated talents of the mystery world.
Forge (with Otto Penzler) will be reissuing Grandmaster soon as part of their program to bring back Edgar winners that have gone out-of-print, so hopefully more readers will have the chance to experience Murphy’s great talent.
I saw the MURPHY’S LAW premier lo those many years ago. As I recall, it was pretty good. I especially liked Murhpy getting the cop to breathalize him to prove to his girlfriend he wasn’t drunk.