There is a subtle difference between fan writing incest for their own pleasure, and a journalist carelessly claiming pseudo-incest (or maybe not so pseudo since it was never revealed how Mundus made her) is canon in the official material, when even Kamiya
denied it.
We know next to nothing about Eva, so I don't feel like I should agree or deny that her and Trish are different. The face is the same at least.
Late reply, but what we know is that Trish was made to look like Eva, like Rebel Dynasty (and you I think) said. According to DMC1 Dante, Trish has her face. So I would assume she's an exact physical copy of Eva. Of course, that doesn't mean Trish is a clone. Clone means made out of the same biological material, the same biological sequences. As far as I know, Mundus simply created Trish, and we don't know how exactly. So I wouldn't say that a clone and a copy are the same thing.
As for demeanor, yeah, Dante said Trish sometimes reminds him of his mother, but in DMC1 he also said that she was nothing like her. Now, he was angry when he said it... maybe he meant that Trish is almost exactly like his mother, but at the same time the complete opposite because of her evil actions... but that's not what Dante said. All he said was Trish isn't like her... so I'll take that as literally as I can.
But yeah, the idea that Trish is Dante's love interest is creepy. Who the heck would hook up with somebody who looks exactly like their mother? If anything, Lady would be his love interest, though I haven't seen anything that says she is.