eiru_voucher_vendor/views/account_voucher_view.xml

<?xml version="1.0" encoding="utf-8"?>

<openerp>
    <data>
      <record id="account_voucher_vendor_view" model="ir.ui.view">
          <field name="name">account.voucher.vendor</field>
          <field name="model">account.voucher</field>
          <field name="inherit_id" ref="account_voucher.view_vendor_receipt_form"/>
          <field name="arch" type="xml">
              <field name="journal_id" position="after">
                  <field name="employee_id"/>
              </field>
              <field name="name" position="after">
                  <field name="employee_id2"/>
              </field>
          </field>
      </record>

      <record id="view_voucher_tree" model="ir.ui.view">
          <field name="name">view_voucher_tree</field>
          <field name="model">account.voucher</field>
          <field name="inherit_id" ref="account_voucher.view_voucher_tree"/>
          <field name="arch" type="xml">
              <field name="reference" position="after">
                  <field name="employee_id"></field>
                  <field name="employee_id2"></field>
              </field>
          </field>
       </record>

        <record id="view_accountvoucher_filter_search1" model="ir.ui.view">
            <field name="name">accountvoucher.filter.search1</field>
            <field name="model">account.voucher</field>
            <field name="inherit_id" ref="account_voucher.view_voucher_filter_customer_pay" />
            <field name="arch" type="xml">
              <search>
                  <field name="employee_id" string="Cobrador Agendado"/>
                  <field name="employee_id2" string="Cobrador Real"/> 
                  <separator/>
                  <group string="Agrupar por">
                      <filter string="Cobrador Real" context="{'group_by':'employee_id2'}"/>
                  </group>
               </search>
            </field>
        </record>

    </data>
</openerp>