I think the reason there weren't replies is that it seems to be working normally.
Early in the Age Unis can easily make attacks result in 0 gains. Even without Unis, it is possible to get 0 gains from Abduct if you don't do your due diligence (GBP is often overlooked early Age). It is also definitely possible for a range of amount of scientists to result in the same amount of losses, given that you couldn't take 5.8, or 6.4 scientists.
You didn't say this province wasn't Orc, just that it wasn't Orc +4h... Orc gains would pretty much cancel out the 31.5% Protection generated by your Universities as you have them listed.
Province to province you guys are in max gains range, but his KD size way smaller, so there is NO gains penalty for him across that KD NW gap, but you would be at the maximum penalty upon retaliating (a nerf of ~33% gains) [
http://wiki.utopia-game.com/index.ph...etworth_Factor ]
Anyways, the best way to deter this type of return customer would be to use your extra 5,796,013 NW to either beat a CF out of the KD or pk the province if you deem necessary.