That's right, but my problem is that two separate tools are giving two separate readouts, about a minute apart, not orbital drift. To rephrase my question, is keosynchronous orbit an orbital period of 1 kerbin day, or 1 kerbin day - 50 seconds, as BBT tells me?
Edit: and yeah, shooting for exact orbits isn't really gonna help, but I also have BetterTimeWarp installed, and since I use ion engines on these probes, I can get pretty precise orbital periods, like down to hundredths of a second.