The twins, which could be up to a week old, are siblings for the museum's first gecko baby, hatched about a month ago.
Their Giant Madagascan day gecko parents arrived at the tropical environment in June from Auckland Zoo.
They had produced a set of twins in Auckland but museum staff had not expected them to breed so soon, museum director Shimrath Paul said last night.
Females generally lay two eggs at a time.
They look like squishy white peas attached to each other and are usually hidden on tree trunks or under leaves.
Incubation takes about three months and babies hatch as miniatures of their parents - bright green with red markings, curious in nature, fleet of foot, and endowed with millions of microscopic hairs on each toe, enabling them to climb any surface.
Like their parents, the offspring eat bananas and flies sprayed with a multivitamin solution.
One baby sat on a handrail for half an hour, chasing flies and stalking butterflies four times its size.
It fell into living environments officer Murray McGuigan's hand, later taking an huge leap on to his head.
Living environments co-ordinator Scott Kerr said female geckos can lay up to six pairs of eggs a year, so there was a good possibility of more baby geckos for the attraction.
