You can't get two of the same GP in the long count. So I presume you got two from the city.
Actually, assuming you got your first Great Person at turn 62, the GP at turn 183 can be another scientist. Once you get all 7, you restart the cycle.
I got 2 scientists from the city in my last attempt. I took GS as first Long Count person, GE as second, but for third and fourth I took Great Admiral and Great General. These two do not increase the amount of points required to get your Great Person with specialist points (though the Great Prophet does, which is weird), so by taking these two I was able to keep the Great Person requirement at 300 long enough to get it with University specialists. Then I got another late in the game around 900 or 1000.