Take for example res.users.csv:

"id","name","email","login","groups_id/id"
"user_example","user example","example@ex.com","example@ex.com","base.group_user,mymodule.group_example_manager"

Both behaves as the following example in xml:

<field name="groups_id" eval="[(6, 0,[ref('mymodule.group_example_manager'), ref('base.group_user')]" />

But I want the equivalent of this:

<field name="groups_id" eval="[(4, ref('mymodule.group_example_manager')),(4, ref('base.group_user'))]" />

How can I do it?