About dataloader‘s dispatch Timing

[xingxingll]

I have a easy query：
query { c1:coin(coinKey:"btc"){ coinBasic{ isInClude } } c2:coin(coinKey:"btc"){ coinBasic{ isInClude } } c3:coin(coinKey:"btc"){ coinBasic{ isInClude } } }

the coinBasic.isInClude has a dataloader to resolver its value.
when i execute this query , i find the coinBasic.isInClude's dataloader dispatch twice.
Observe by debug ,i find the dataloader dispatchall first on c1 and c2, dispatchall second on c3.
why it need twice dispatch.I think one dispatchall is enough.