Comment by dragonwriter

> N pieces of code that are mostly the same but have subtle differences isn’t repetition

Often, they are.

IME, a very common pattern is divergent copypasta where – because there is no connection once the copying occurs – a bug is noticed and fixed in one place and not in others, later noticed separately and fixed a slighly different way in some of the others, in still others a different thing that needs done in the same function gets inserted in between parts of the copypasta, etc. IT’s still essentially duplication – more over its still the same logical function being performed different places, but in slightly different ways, creating a singificant multiple on maintainance cost, which – not literal code duplication in and of itself, is the actual problem addressed with DRY, which is explicitly not about duplication of code but single source of truth of knowledge: “Every piece of knowledge must have a single, unambiguous, authoritative representation within a system”. Divergent implementations of the same logical function are different representations of the same knowledge.