Reminds me of the video driver (forget card) some Linux developers wrote that was ~30k lines of code. OpenBSD wanted to use it because the HW manufacturer wouldn't release the specs, but because the Linux code was GPL, the OpenBSD guys re-wrote it from scratch in less than 1/4 of the code.
Further, that the code probably would not really be hideously miserable for a more experienced coder to refactor(it's just very duplicated) shows that copy-paste is reasonable for deferring some kinds of architectural decisions. It's not what you would bias towards if you have a whole team pounding away at the same file and rapidly evolving it, but as a solo practitioner who wants to get the feature out and put it away for the day, this style is convenient for letting the code as a whole develop some maturity and functionality before it gets refactored with abstraction.
yup. reminds me of: "Write Code Like You Just Learned How to Program" -- https://prog21.dadgum.com/87.html