Image widget inside O2M form widget asks to save each register

If an image widget is defined inside an O2M form widget (for example a photo for every contact -address- in the partner form):

  <record model="ir.ui.view" id="view_partner_form_mcard">
   <field name="name">res.partner.form.mcard</field>
   <field name="inherit_id" ref="base.view_partner_form"/>
   <field name="model">res.partner</field>
   <field name="type">form</field>
   <field name="arch" type="xml">
    <field name="email" position="after">
     <field name="photo" widget="image" colspan="4"/>
    </field>
   </field>
  </record>-

When we change the register (previous, next) without changing any information, the client asks every time to save the form.