You could be forgiven for seeing more than double at one Co Down primary school.
Amazingly, there are no less than four sets of twins among the new P1 pupils that have joined St Mary's Primary, Saintfield.
It's highly unlikely that another primary school in Northern Ireland can claim to have welcomed such an unusual number of twins this new school year.
It's as simple as A, B, C, or perhaps 2-plus-2 for the non-identical, or fraternal twins, as they start their school career.
Despite having the comfort of a brother and sister in the same class, the twins are very content to be treated as individuals
While there's some adult fascination at such a rare occurrence in a small country school, the twins have been readily accepted by their new classmates.
And if by chance a teacher or other grown-up gets their names mixed up, the twins and classmates are very quick to point out who's who.
There are two sets of boy twins, one set of girl twins and one brother and sister.
Aimee and Erin Braniff (4) are adorable sisters and while looking very alike, they can be easily distinguished by slightly darker hair colour and eyes.
Curly-haired Dylan and Ryan Walsh-Williams (4) also look very alike but Ryan's glasses help set him apart.
Luke and Patrick McSorley, also aged four, are unmistakably brothers but Luke loves to point out that Patrick is bigger.
As for twins Rex and Ria Sunny (5), the fact that they are brother and sister makes it much easier to tell them apart.
"While the twins are not identical, they are very, very alike.
"Myself and the classroom assistants know who's who, when some of the other teachers perhaps mix them up, well, the twins and the other children are very quick to put them right," joked teacher Maeve Haughey.
This is the first time in a career that has spanned 23 years that Miss Haughey has taught one set of twins, never mind four.
"We encourage the twins to be seen as individuals in class and the other nine pupils have also easily accepted the twins as fellow pupils in their own right."