Position control question

I have an existing position that was once title Benefit Specialist and was set as salary. The current employee had agreed to go into an on-call status (hourly)until we can get the new candidate trained. Since then we have retitled the current position to be a Comp & Benefits Mgr and the status has changed to Salary and hired someone. Due to both employees working, one hourly and one salary, would I have to create another position code even though the employee is really replacing the one that had agreed to stay on in an on-call status? I hope this makes sense and I appreaciate any guidance you can give me. Thanks!