Checking which account is honest isn't too hard, you detect that there is a "problematic mismatch" between two clients. So the project runs their own client to

Checking which account is honest isn't too hard, you detect that there is a "problematic mismatch" between two clients. So the project runs their own client to check. If one has an exact match, then you'd question the other. There is a challenge for sites that serve different content based on GeoIP, A/B testing, dynamic content, etc. So some human review of the diff may help check for malice. If there's literally spam, human review would clearly detect this and that bot is distrusted.