$form['submit1']=array(
        '#type' => 'submit',
        '#value' => t('Submit form 1'),
        '#submit' => array('::processForm1'),
        );

$form['submit2']=array(
        '#type' => 'submit',
        '#value' => t('Submit form 2'),
        '#submit' => array('::processForm2'),
        );

$trigger=$form_state->getValue('op');