To reproduce :

• Go to a course using competencies
• Click on: Navigation block > Home > Courses > My course > Competencies
• Click on any competencies
• With any user, Under rating section, click on the "Rate" button

A solution may be to not use a button for the cancel one but a input instead.
Also, I think the buttons should be in the moodle-dialogue-ft div instead of being in floated right div followed with an clearfix div inside the moodle-dialogue-bd section.