Stopping the 2nd accounts isn't going to stop what's happening, or, what's perceived as happening.
Let's say 2 countries are banging on the 3rd. Squaddies from 3rd country are assigned to other countries to report back activities of 2 countries and try to start up something between them or pork the others factories, etc, etc. Or it could just be players that agree to work together to accomplish some goal.
"spying" and "sabotage" doesn't need shade accounts.
what is this? the "Spanish Inquisition"?