It seems I have caused offence in my choice of answer to my question today.
Have I broken any rules ?
The faq on Meta states "The bottom line is that you should accept the answer that you found to be the most helpful to you, personally."
Stack Exchange isn't a quiz show, so it doesn't matter which answer is first (as long as the later one isn't plagiarizing the earlier ones), it matters which answer is the most helpful to you.
Before comments are deleted
Not that important, but my answer was the first to suggest "sextile" – user2922582
...anyway, a quick search would have given you the same result. Please do your own research before asking. here. Nothing personal! – user2922582
My choice was based on what I saw when I used the appropriate links and my choice was based on my own aesthetic appreciation and my own personal opinion. A pleasant day to all contributors. – Nigel J
[emphasis in bold, mine]
@user2922582 there's one minute difference between your post and that of Perry's, possibly less. IOW you posted the same(ish) answer. What the OP could have done was to wait a couple of hours before accepting an answer to see if other solutions turned up (doubtful in this scenario but you never know) – Mari-Lou A
There is no rule saying that an OP has to accept the first correct answer posted, but it's good policy to wait a while before doing so, to allow users in different time zones to post their contributions.
The only rules here are the ones enforced by software. I suppose one could be allowed to vote more than once on a given item, but there is a rule, enforced by the software of SE that you can vote at most once.
Anything allowable is not rule bound. There may well be a strong suggestion or guideline (Like those in close reasons or general behavioral common courtesy), but those are not hard and fast rules.
It would seem weird to accept a later answer that is almost identical (that's just common courtesy), but maybe the wording of the later one had better references, or made more sense, or didn't have readability problems.