contrapose!
d n : ℕ
f : (p : ℕ) → p ∈ n.primeFactors → Fin d
hf : f ∈ n.primeFactors.pi fun x => univ
g : (p : ℕ) → p ∈ n.primeFactors → Fin d
hg : g ∈ n.primeFactors.pi fun x => univ
⊢ Nat.primeFactorsPiBij d n f hf = Nat.primeFactorsPiBij d n g hg → f = g
d n : ℕ
f : (p : ℕ) → p ∈ n.primeFactors → Fin d
hf : f ∈ n.primeFactors.pi fun x => univ
g : (p : ℕ) → p ∈ n.primeFactors → Fin d
hg : g ∈ n.primeFactors.pi fun x => univ
⊢ f ≠ g → Nat.primeFactorsPiBij d n f hf ≠ Nat.primeFactorsPiBij d n g hg