Behat failures on feedback module during parallel runs

While the feedback with groups scenario runs perfectly in a single instance, it fails in parallel runs:

001 Scenario: Non anonymous feedback with groups in a course # mod/feedback/tests/behat/groups.feature:66
And I log in as "user7"                                # mod/feedback/tests/behat/groups.feature:128
Field matching locator "'Username'" not found. (Behat\Mink\Exception\ElementNotFoundException

002 Scenario: Anonymous feedback with groups in a course # mod/feedback/tests/behat/groups.feature:169
And I log in as "user7"                            # mod/feedback/tests/behat/groups.feature:238
Field matching locator "'Username'" not found. (Behat\Mink\Exception\ElementNotFoundException

Perhaps the function i_log_in_as_and_complete_feedback_in_course should not use "the quick way" ....