Best practice to improve own answer

Question

If someone posts a detailed answer, with step by step, screen captures... gets votes, and it occurs that :

• the answer doesn't solves fully the issue
• the answerer finds the exact solution
• but that solution is partially or completely different from the original one

Is it better to :

1. leave the original one intact, and post and edit below ? (does not "betrays" the existing votes)
2. completely rewrites it ? (better for readability and future use)
3. write a second answer besides the first one ??? (looks confusing)

Answer 1

It is rare that I've seen any multi-answer replies to a question by the same user.

Typically, the practice is to just to update the existing answer for whatever reason that the question has changed the context (e.g. UI updates no longer reflect instructions, a question has been updated with a left out detail, etc.). If preserving the original answer is important, you can insert some header noting postscript changes (e.g. "Edit: Answer worked in Drupal 8.3.x, added info for Drupal 8.4.x") into the body of the answer.

I'd say the only reason to add a 2nd answer is if the answer takes a completely different approach to the question, thus violating what the original answer achieves. For example, an answer might take a site builder approach (e.g. add & configure this module) or a developer approach (e.g. add a custom module and plug into the relevant APIs) which will solve the problem for 2 different sets of people.