WET code (opposite of DRY code, often starts as copy pasted) has more code, more typing, but the diffs are simple, bugs are simple (often you simply forgot to copy piece of code into 7 different places which is easy to solve). After many iterations, what started as very similar "classes" is now completely different.
One look at WET class and you know what it does, you change one line and you're done, maybe you need to copy it to 2-3 other files, maybe you don't. In comparison, you'll stare at DRY class for 2 hours and realize you need to refactor absolutely everything, it will break half of the codebase and diffs are insanely complicated.
I've recently wrote 2 similar projects, one wet one dry and wet one is simpler, easier to maintain, and more enjoyable to work on. Dry is root of all evil.