Thanks. Usually HN detects dupes, but looks like in this case, the url was slightly different. It would be good if HN detected dupes in titles and provided a warning. So that I can tone down my expectation of reactions from the HN crowd :)
I'm getting a 403 from that link.
Just tried it again and it works for me (in the UK). Cleared browsing data and everything, and tried in another browser.