You may not have an explicit rand(), but with the ligatures & substitution rules, you can add so much context sensitivity that no one will ever spot any duplications.

That's how you can do things like https://litherum.blogspot.com/2019/03/addition-font.html https://pagedout.institute/download/PagedOut_002_beta2.pdf#p... https://aftertheflood.com/journal/the-worlds-first-code-free... https://www.coderelay.io/fontemon.html (most of these will work in a browser). I've also suggested that you can create 'prank fonts' which add in subtle typos sporadically.

Less evilly, this is what calligraphy handwriting fonts do to get convincing variation.