Copyright protection was my first thought too, similar to how cartographers used to put “bunnies” in their maps to identify copycats.
https://www.sfgate.com/news/article/Mapmakers-sleight-of-han...
https://www.sfgate.com/news/article/Mapmakers-sleight-of-han...
[1] http://gally.net/leavings/00/0091.html
[2] https://en.wikipedia.org/wiki/Lexicographic_error
[3] http://listserv.linguistlist.org/pipermail/ads-l/2001-Decemb...