@BelindaWilson I think we must have confirmed at the same instant!
@jmcleod twins happen in EGKS about once in a thousand females. Researchers in ACT gov have seen them at all ages. It is unclear how many are genuine twins in the sense we humans would think of twins. Many are from a failure of pregnancy to prevent one additional ovulation so the two young differ in age by the length of the oestrus cycle. And there is another phenomenon in marsupials (so far only recorded in EGKS) which could produce the appearance of twins. Mothers swop young. A surprising proportion of pouch young are not the offspring of the pouch owner, not even closely related. So hypothetically, a pair of older twins could arise as a result of that type of event, with the two taking turns to suckle from the same teat. That is purely speculative. There has been too little observation of the right type, of these uncommon events, to know whether it happens in practice.
@DonFletcher thanks for the info. Pretty sure it's the first time I've seen two joeys in one pouch, so I assumed it wasn't common. you're welcome to. Not sure if NatureMapr shrinks photos - if so, I can provide the original (or a few others, but that's the clearest). Can be credited to J McLeod or Jenny McLeod.