That would be rare indeed. No offense, but what are our sources?
I don't know if it was actually released for C128, but there is a reference to some technical tricks used on that platform in an interview of Robert Woodhead, published in the QuestBusters Adventurer's Journal from march, 1987.
The article is about Wizardry in general, starts at pg4, and pg9 has the Wizardry 5 & C128 specific information. This interview precedes the actual game release, so what actually was released I don't know.
In looking into this one it appears to utilize C128 mode to take advantage of C128 specific features (namely all 128K memory and the increased disk reading speed of the 1571 drive). It didn't come as a separate release but was included with the C64 version. Did I make a mistake about this one? Wikipedia notes "Lengthy load time and extensive disk access was a problem with Wizardry; however, the Commodore versions, which particularly suffer from this, provided a variety of workarounds. In C128 mode, the VDC memory is used to store overlays and REUs are supported in both C64 and C128 mode. Wizardry 2-5 also detect if 16k or 64k of VDC memory is present and can use the 1571 drive's burst mode for faster load time." and I found several forum threads that seemed to state more or less the same thing.
Wizardry III is currently pending and I think it does the same thing though I haven't looked at that further yet.