Without a drastic change in the law, I'm going to consider here that the law relating to abortion as to when "life starts" would be the blanket ruling on this. Also, IVF principles are so close to cloning in moral regards that to class a clone as not human would surely mean a test tube baby would receive less rights?
If you take the situation in the film: The Island, the clones were not supposed to be sentient, when in fact they actually were, this hidden away from the general awareness of society. As a fictional representation, those who would regard the situation described as allowable will be very few, and I'd suggest their humanity was in question.