The system maintains a single applicant as the Active Applicant for a user, and that will remain so until the user changes the active applicant to a different one by going to:
Applicant record
Action
Set as Active Applicant
Now, if users are using that Send CV Active Applicant menu option from within a job record thinking that it will be the last applicant record they happened to look at - no it won't be, it will be that semi-static Active Applicant time and time again while they continue to use that menu option and while the Active Applicant has not been changed by the user.