This is an interesting discovery! Jackpot numbers are unique. They are not repeated. They don't win the second time.
After I had entered all the jackpot numbers from all the Philippine system-6 lotto drawings (there were only 6/42 and 6/45 then), the very first thing that my program did was to check any duplicate entries. If there were, I had to verify if my data were correct. After each correction, I would run the program again until there were no more errors. When my program was no longer showing duplicate entries, I realized that that means the jackpot numbers were all unique! Interesting! For that reason, that finding pushed my curious mind the more to perform more extensive tests.
From time to time, I would test this fact. When lotto 6/49 was born, the fact remained the same until October 11, 2006 when the numbers 1, 4, 9, 16, 36, 37 won from Mega lotto 6/45. The same numbers won on September 22, 1999, also from Mega Lotto 6/45.
Based on 3,867 4012 results, only two of them are exactly the same. This is the very first and only jackpot numbers that won twice. No other jackpot numbers were ever drawn more than once.
Even if there exists already one instance of jackpot numbers winning twice, the probability of this to happen again is very low – 1 instance for every 4012 draws. For that reason, it remains wiser to play lotto numbers that are unique. That means, your 6-number lotto combination that you wish to play must remain unique — never been drawn before.
Update: 5,805 jackpot numbers were gathered. This already includes jackpot numbers from Lotto 6/55. As of today (4/24/12), the fact remains the same that only one jackpot numbers had won twice. That means for every 5805 draws, 2 have the same jackpot numbers; or 2:5805 or 0.03%.
The Probability of Each Number
The Odds of Winning