Multiple Integrals give different results

[Veenty]

So I'm doing iterated integrals and there is something funky when I composite them So for example Evaluation(Chebyshev(), -1)*Derivative(Chebyshev(),1)*Integral(Chebyshev(), 1) - Evaluation(Chebyshev(), -1)

Gives me the 0 vector, however

(Evaluation(Chebyshev(), -1)*Derivative(Chebyshev(),1)*Integral(Chebyshev(), 1))*Integral(Chebyshev(), 1)*Integral(Chebyshev(), 1) - Evaluation(Chebyshev(), -1)*Integral(Chebyshev(), 2)

Does not give me the 0 vector, I get

PlusOperator : Chebyshev() → ConstantSpace(Point(-1)) 0.0 0.125 2.77556e-17 -0.125 3.46945e-18 -1.73472e-17 2.1684e-17 -4.33681e-19 6.72205e-18 4.77049e-18 ⋯

[Veenty]

So it turns out that applying iterated integrals is not the same as applying Integrate(Chebyshev(), 2). However Integrate(Chebyshev(), 2) = Integrate(Chebyshev(), 1)*Integrate(Chebyshev(), 1), which honestly I think is quite confusing