How to create a new report based on an existing one?

<template id="report_saleorder_document2" inherit_id="sale.report_saleorder_document" primary="True">
...

<template id="report_saleorder">
    <t t-call="web.html_container">
        <t t-foreach="docs" t-as="doc">
            <t t-call="sale.report_saleorder_document2" t-lang="doc.partner_id.lang"/>
        </t>
    </t>
</template>