How would a mum of twins take her bubs out alone, if she's wearing one, how else can the other be moved around?

Double/Twins stroller might be a better option if the babies are still young. phil and teds double stroller is easier to push around and safe. If the twins able to walk already, while wearing a baby, you can choose to either put another one in stroller or using a safety strap to hold the child.

If u want less bulky and better ways is, a light weight stroller that can recline, and baby wear 1 baby. Rotate it. Sometime when baby carry non-stop, mummy still need to babywear it, so whether pushing a double stroller or not, good to standby a baby carrier.

There is such a thing as tandem wearing, where both children are carried simultaneously. The weight might be too much on the shoulders though, so she could get a stroller to push her other baby around.

Many options for babywearing twins. Have a look in this Tandem Babywearing international group: https://www.facebook.com/groups/tandembabywearing/

bought a twin stroller for my twins when they were 4 months old only

thanks

twin stroller will work well..