If I clone myself before I go to bed and wake up to find that my clone ate the last of my cereal, then I'm not magically full of food. I'm still hungry. My clone is full, but their experience of eating the food and being full is not mine. Even if I had watched them eat it, my experience would be of watching them eat, and not having eaten it myself. It doesn't matter that they are technically me.
While in the game they are a direct duplicate of yourself, an actual clone would not be. It would be the same as if you'd had a biological twin at birth. Genetically the same, but an entirely separate individual.
They stopped being entirely me once they split off. Unless I was somehow physically in control of both bodies at once, there is stuff going on that I am not directly a part of. Hence, it feels like I'm being left out of it, whether it is eating that cereal, or banging one orifice on a woman while my clone does another. It's always going to come down to there being an "other guy" in the bed with you and the woman.
I won't argue that. I guess the real question comes down to the MC being an idiot and constantly making the double disappear after the act is completed. Does the (now singular) MC contain memories of fucking both women, or from both positions with the same woman? Which one constitutes the Real MC? Did he fuck Jessica or Elizabeth? Did he creampie Zoe or Megan? Post-disappearance, are both girls dripping goo?
Despite the pleasure holes, there are a lot of holes in how this was executed, and even more in the answers department. That said, if I could have magically duplicated myself to DP my highschool girlfriend, i totally would have. She'd have been into it, and I certainly wouldn't be worried about whether or not she'd like the other guy more.
Of all the girls in this game, though, I'm only mildly disappointed that Chloe didn't get "the treatment". If there was any character who it seems would thoroughly enjoy it, it would be her.