Today I did a little test. I wanted to have the choice of sleeping with both of them in the end, free, but I had no save where I had made both requirements, "slept" with Josy and Maya.
So I started a new game and, instead of following the Chick steps, I was completely DIK, all the choices.
In the end I managed, with respect to the sex scenes or partial (at least one), to have all the MG and most of the SG. I think he only missed Rose and Melanie, one for not choosing Derek's door, the other for not choosing Sage's. Both are not even officially listed as SG anyway. There was no scene in the bathroom with Jill, but there was the kiss.
So in the end, the time for the big reveal, I just switched my DIK affinity to neutral. And boom, the two accepted and the three slept together. Of course, staying with them you miss the final scene with Jade, but as there has already been foot&hand job...
Harem save, right here
Which makes me think... After all, why the hell DPC choose to end the dreams of the DIKs who wanted both at the same time? You can have all the others in the same save, except for them.
The only ones you lose in this story, for good, is either Jade, because I doubt that she would give the MC another chance, or both together (M&J), as I still don't rule out the chance to have just one of the two in the future.
Soooooo.... Having both, at the same time, is the reward for the Chick path, since at DIK you have MUCH more girls and scenes. He must have thought, "nothing more fair then giving two MGs, to make up for the lack of all the others".