Not long after the HSC ancient history exam finished about lunchtime on Thursday, students were on a popular website comparing notes about their feelings of deja vu.
They had noticed that the exam had many questions similar, or in some cases identical to, the Catholic schools trial HSC paper thousands of students sat in August.
"HSC paper practically identical to Catholic trial," one student posted on boredofstudies.org
"Yep, the Xerxes questions were incredibly similar, too. I had the strangest feeling of deja vu," another wrote.
Both papers were set months apart by separate committees. The HSC paper was stored under lock and key in a warehouse from July. The Catholic schools paper was finalised on February 4, and students at Catholic, independent and public schools sat it in early August.
An analysis of both papers shows that a third of the 76 HSC questions had similar wording and content to the Catholic paper.
In the "Personalities" section, accounting for a quarter of the exam mark, every (a) and (c) question for the three-part essay had the same content. Three of the 12 elective options had the same content for all parts of the question.
The NSW Board of Studies, which sets the HSC exams, said in a statement: "It is pure coincidence that two separate groups of ancient history educators have developed some similar questions in this exam."
Many students could not believe their luck. One gloated on the boredofstudies website: "He, he ... I got 25/25 in the trial ... and wrote fairly similar things. So here's hoping."
Catholic school students account for a quarter of the 66,000 HSC candidates. More than 9700 students from all schools sat the history exam.
Public school teachers who contacted the Herald, but cannot make unauthorised media statements, were concerned that Catholic school students would have benefited from teacher feedback after the trial exams.
The Board of Studies spokeswoman said the two exam committees that set the questions had no common personnel.
The ancient history exam committee included only public school teachers and university academics.
Both the board and the Catholic Secondary Schools Association of NSW, which set the Catholic schools paper, said the best explanation was that both committees had stuck closely to the year 12 syllabus.
The slight differences in wording in the Personalities section, for example, "can be quite significant in terms of assessment", the board's spokeswoman said.
The HSC paper asked about Alexander the Great's "relationship with his army and generals", while the Catholic schools paper quizzed students on his "relationship with his generals".
"That both papers would include a question on Alexander's relationship with the military is unsurprising given the significance of military campaigns to his life," the board's spokeswoman said.
John Cook, convener of the Catholic schools trial HSC exam program, said the similarities showed that "both agencies have picked the central elements of the syllabus".
Mr Cook said his organisation supplied trial exam papers to 52 per cent of schools doing the HSC, including a number of independent and public schools.
It was not uncommon for exam papers to have similar questions. "We would simply stress the integrity of both of the [exam] processes, which ensure that no student has an unfair advantage," Mr Cook said.
"Significant numbers of government schools use the Catholic trial paper because it is a good examination.
For the first time since the HSC overhaul in 2000 more students this year took ancient history than modern history. It is now the ninth most popular subject.