Because that isn't how the science works. An embryo comes from the egg of a single human female, otherwise you'd have two or more embryos, each from a single egg of a single human female. An embryo is created when sperm fertilizes that egg. If two sperm fertilize the same egg you end up with 69 chromosomes and a higher chance of miscarriage, and to avoid this the egg actually haws two outer layer to help prevent this from happening.
Because that isn't how the science works. An embryo comes from the egg of a single human female, otherwise you'd have two or more embryos, each from a single egg of a single human female. An embryo is created when sperm fertilizes that egg. If two sperm fertilize the same egg you end up with 69 chromosomes and a higher chance of miscarriage, and to avoid this the egg actually haws two outer layer to help prevent this from happening.