Hey, I am really sorry for posting this. I didn't know it was posted earlier too! I thought this might be a good post to discuss on HN. Is there any way of knowing if the content is posted earlier on HN?
HN does have a dupe detector and won't let an identical URL be posted a second time. But, as you can see in the above comments on this same page, even very slight differences are sufficient for it to allow the post through.
Anyway, I hope you keep posting items like this! If they're not sufficiently interesting and novel to enough people, they won't be upvoted. No harm.