Line Mangers vs. Salary Manager role and security

Summary:

We have Line Mangers and Salary Managers (matrix managers), the Line Managers do not have access to view their subordinate's salary or compensation information, while salary managers have view/update access to salary or compensation information.

The Salary Managers can also have people reporting to them (so they have the line manager role), but in some cases, they are NOT the salary manager for their subordinates, so while they have the salary manager role, they should NOT be able to view/update the salary information for the employees where they are not the salary manager.

We copied the Line Manager role to create a Salary Manager role, and applied security based on the matrix manager access, however, when a line manager is also a salary manger, the salary manager role supercedes the line manger role and the salary manger can view/update all of his subordinate salary info, which we do not want. He should only be able to view/update the employees where he their salary manager. I believe this is standard functionality.