Thanks for the input everybody.
I think the current owner did not realize that he has copies and not originals.
I did talk to the previous owner who knew about the logs when he bought the plane a while ago. He had excellent reasons for buying and for selling and he seems like a really top notch guy. I'd previously found lots of information about him on the web and talking to him just convinced me that what I read was true.
The owner before that was the IA who copied the logs because they were in such bad shape, but he doesn't seem to really remember if he copied the originals or a copy - that was 5 or 6 years ago and it was too many years and too many planes ago. According to the IA, the owner before that was "just a pilot" who probably knew that logs existed, but not much more. I can only conjecture on what happened to the originals.
I have the actual originals from 1999 on but copies of the logs before that. I have the FAA CD also, and everything seems to line up with them. Since 1999, the plane got new radios, new paint, and new engine (now past TBO) so all the really major stuff is covered. It is going to get a new or rebuilt engine pretty soon, if I proceed with the purchase.
I'm not at all worried about the condition of the plane. My mechanic did a full annual on it instead of the customary pre-purchase inspection. I am no more or less worried about if I am getting a "good deal" than I was before this issue cropped up. I just don't want to take a bath if I end up having to sell. (My current plan is to NEVER sell the plane, having regretted selling my old plane for a year and half now. But stuff can happen.)
I can tell you that the term "copies of the originals" is rather ambiguous in this situation! That could mean "originals" or it could mean "copies." In this case, it appears to mean the latter.