Quokkas

Quokkas give birth twice a year, single joey at a time.

An excerpt from the article 25 facts about Quokkas
A joey is born after a month of gestation. The tiny youngster resides in mother’s pouch for about six months. Upon leaving the pouch, joey nourishes with mother’s milk for another two months, after which it becomes fully capable of living on its own.

Quokkas birth up to 17 joeys in their lifespan.