No, for me a single ticket is enough entry to win the jackpot if one is destined to win.  In my view, buying extra ticket is just a waste of money.  If one will win, he will win, even if he buy only one ticket.  This had been a proven case where many people had been buying more than one tickets but they failed to win a jackpot price.  Remember only one number combination will win the jackpot price so any other number combination one buy is a waste or money besides, adding one more ticket may probably increase your chance to win to 100% but in overall statistics that chance does not even 0.1% increase to win the jackpot price.