And the European hare does this mating while they're pregnant-a phenomenon known as superfetation.
欧洲野兔也在怀孕期间进行交配，这种现象被称为‘异期复孕’。
英语百科
Superfetation
Superfetation (also spelled superfoetation – see fetus) is the simultaneous occurrence of more than one stage of developing offspring in the same animal. In mammals, it manifests as the formation of an embryo from a different estrous cycle while another embryo or fetus is already present in the uterus. When two separate instances of fertilisation occur during the same menstrual cycle, it is known as superfecundation.