Enjoy your completely unique pattern. No one will ever see it again.
Every time a mass is added, the system generates new random starting angles and velocities for all masses in the chain. Across the session, that's 48 independent random values, each with 52 bits of precision (~4.5 × 1015 possibilities per value).
The total number of possible patterns this experience can produce:
(4.5 × 1015)48 ≈ 10750 possible outcomes
The physics is deterministic: same starting conditions always produce the same motion. The pattern you saw is entirely defined by those 48 numbers. Reproducing it would require matching all 48 exactly.
This will never happen in practice, not if every human on Earth ran this simulation every second until the heat death of the universe.
How unlikely? Winning the Powerball jackpot 88 times in a row is roughly the same odds. There are approximately 1080 atoms in the observable universe, and this number is larger than that raised to the ninth power. A UUID collision, the thing engineers consider "impossible enough" to bet entire databases on, is 10714 times more likely.