With two sets of twins already enrolled, the school will add another four sets when prep classes begin on Monday.

Prep teacher Barb Van Egmond said teachers and pupils may be struck by a severe case of double vision.

But she hoped to avoid trouble with an old-fashioned but effective strategy.

"They'll rely very, very heavily on nametags," Ms Van Egmond said.

While it is expected identical twins Tyler and Aiden Cox and Mia and Jade White will create the most havoc in deciding who is who, non-identical twins Jessica and Amy Morgan and Benny and Willy Whitehouse are very similar in looks as well.

Mia and Jade's mother, Karen White of Greendale, said she had tried to help.

"The girls have had their ears pierced and we've given Jade green earrings," Mrs White said.

But Donna and Wayne Cox, also of Greendale, weren't sure how staff and students would go telling their boys apart.

"Other than close family and friends, people find it very hard," Mrs Cox said.

"They certainly had trouble at kinder."

For Blackwood mother Sam Whitehouse, Monday will have a touch of deja vu.

Her five-year-old sons Benny and Willy will begin at school two years after her first set of twins finished grade six at Myrniong.

"You have to make sure you divide the time so they get what they need," Mrs Whitehouse said.

"You just have to become more organised."

As for a theory behind the Myrniong twin phenomenon?

"Rainwater?" suggested Tamara Morgan, mother of Amy and Jessica. "I really don't know, but you do get double the cuddles."