Having a partner on four servers with the same domain name. Two servers serving my ads and two servers serving his?
You should contact the adsense team really, in any case I believe that you mean something like an ads rotator, but in this case it's a hardware one. Depending on the server to where you're connecting either you show one Pub ID or the other. I don't think that might me a prob, as a lot of sites do that. DP for example uses a revenue share script that shows different ad pubs on the same page for different people. In your case it's the hardware doing it. As long as the same page shows only 1 pub ID at a time i don't see a prob, but to stay on the safe side you'd better contact Google and explain very well what you want to do.
i think you must directly contact with the adsense support. it's a problem that i have heard for the first time. i also suggest you not to believe anybody accept adsense support about this