Right, but not if the chromatids in Adam’s chromosomes were somehow nonidentical and got switched around to make Eve’s Xs. Because, if we label the chromatids of his X chromosome as Ia and Ib, and those of his Y as Ic and i (the short chromatid), then the chromatid choices for Eve’s two X chromosomes could be Ia+Ic for the first X and Ib+Ic for the second X; Cain could inherit an X chomosome made from Ia+Ic while Abel could inherit one made from Ib+Ic, and so they would be genetically distinct not only from Adam but also from each other, even if all three shared identical Y chromosomes.
I admit it’s a contrived scenario, but … a parthenogenetic origin for an XY male would be even harder to conceive.