i just tried like this .

<record id="view_order_form_duplicate" model="ir.ui.view">
<field name="name">sale.order.form.duplicate</field>
<field name="model">sale.order</field>
<field name="inherit_id" ref="sale.view_order_form"/>
<field name="arch" type="xml">
<xpath expr="//form" position="attributes">
<attribute name="duplicate">False</attribute>
</xpath>
</field>
</record>

but its not working :(
please help me !!