AI that detects AI seems entirely plausible. And like all “anti” measures, is another arms race (and if I put my scifi hat on, is what may lead to AI self-awareness).
Link to talk: https://www.youtube.com/watch?v=ObhK8lUfIlc
The anti-spam software loses because eventually having self-aware AI view spam calls 24/7 was considered torture and they weren't allowed to go that far.