firebase - 如何合并来自同一路径的 2 个对象？

Question

我有以下结构：

billing: {
   bill1: { 
     creationDate: '2016-01-01', 
     buyer: "person1", 
     seller:"person2"
   }
}
people : {
    person1 : {
        name : "Jane"
    },
    person2 : {
        name: "John"
    }
}

我通过以下方式加入路径：

var norm = new  Firebase.util.NormalizedCollection(firebaseRef.child("/billing").orderByChild("creationDate").startAt(startDate).endAt(endDate),
                [firebaseRef.child("/people"),"people1","billing.buyer"],
                [firebaseRef.child("/people"),"people2","billing.seller"])
                .select("billing.creationDate",{key:"people1.$value",alias:"buyerDetails"},{key:"people2.$value",alias:"sellerDetails"); 
return norm.ref();

当我尝试此代码时，我在控制台上收到“重复路径”错误，显然这是一个限制，你能确认吗？