Instructions are available in the Staff Administration User Guide, chapter 8 from p.15 

Note:  Determining which action is appropriate may require further investigation of data in both eduPay and CASES21. Where multiple matches are found, for example, there are 2 INAC/LEFT staff records with the same details, selecting actions for both records will result in a message that only 1 will  18 be processed. You can progress with processing or return to the main screen to amend your selections.