What happens once will never happen again. But what happens twice will surely happen a third time.
You already know that everything, EVERYTHING, is made of particles and particles are really just wavering energy. All that we could ever perceive and all that we can ever measure is made of waves of energy; literally nothing is solid.
And, see, if you give a wave function the vertical line test, you can't cross it more than once. But if you follow it's domain, it encompasses all. Always. Twice, and three times.