They were getting tired of their own company and wanted to see their friends again.
"Possibly, it was a case of too much of a good thing."
The girls started their second year at Milton Primary School yesterday, and were particularly looking forward to physical education and art. Charlotte said they each had their own group of friends, but still hung out together when they could.
"When we were 5, we used to play with each other lots, but now we play with our friends heaps."
They are in different classes this year, which principal Tania McNamara said would allow the girls to develop their individuality.