Forced to have only one Task Action Field

Question - it seems that you can only have one task action field in a process.  I have a process that has two levels of approval after submission and in my InfoPath form's data source I have a data element for each approval.  Lets say manager 1 and manager 2 (I am keeping this simple).  On the first client event the task action field to the Manager 1's approval data element.  Then I go to the second client event and set the task action field to Manager 2's approval data element.  Then when I go back to the first client event the task action field has been changed to Manager 2's approval data element.  What would this be occuring?

Thanks,
Jason