Along similar lines in both the digital and non-digital world people would include false landmarks and roads on maps to detect copying, since while facts are not protected, fake places are https://en.wikipedia.org/wiki/Trap_street
When I was at Malwarebytes we would seed our engine with "malware" that was just programs we created on an airgapped machine so we could see when other companies were just blatantly copying us.
Code Traps:
https://arcadeblogger.com/2019/06/29/atari-centipedes-hidden...
And the discussion here a month ago about code traps: https://news.ycombinator.com/item?id=20312256
Along similar lines in both the digital and non-digital world people would include false landmarks and roads on maps to detect copying, since while facts are not protected, fake places are https://en.wikipedia.org/wiki/Trap_street