Hello there,@Patrycja.
In QuickBooks, the user, employee, or vendor's profile info, such as first name, last name, and email address, is matched with QuickBooks Online Payroll and QuickBooks Time (QBT). QBT imports them as 1 team member.
To avoid the override of the previous employee in your TSheets. You'll need to change the name of your new employee. You must ensure that each employee has a unique identifier in QuickBooks like adding a middle initial of your employee. You can also add numbers as long you create a distinction. Once you have ensured all employees have unique identifiers and adjusted the names, re-import the employee data.
Additionally, I included an article if you want to manage and modify team member permissions: Manage team member settings and permissions in QuickBooks Time.
If you have any other concerns about managing your employee's name, please feel free to use the Reply button below.