Assign to wrong taxonomy term when importing nodes

I have a taxonomy as below:

-food
--apple
---lemon
--banana
---lemon

food is the parent terms of apple and banana. Both apple and banana have a chile term with same name lemon. When I import a node with csv file:
title,foodname
food1,banana\lemon

I use tamper to add a plugin explode to foodname so it know how to read multiple terms. The progress is work. But, when I check the node, the foodname filed was tag with banana and lemon(which is the chile term of apple....) .What's wrong with my setting...Please help