I just came across the article "Rule of Three" in wikipedia
Rule of three is a code refactoring rule of thumb to decide when a replicated piece of code should be replaced by a new procedure. It states that the code can be copied once, but that when the same code is used three times, it should be extracted into a new procedure. The rule was introduced by Martin Fowler in Refactoring and attributed to Don Roberts.
I know that this is just a rule of thumb, but why is it recommended to refactor only after the second duplication? Is there any downside to refactoring when we write the first duplication?