Can we create a contingent worker with the same employee number of an ex-employee

Summary:

We are trying to terminate around 500 employees and create them as Contingent workers within the organization. The catch here is that the new contingent worker must have the same employee number as before so as to not lose access with the down stream applications.

As the number is high, we are trying this out using a HSDL. We are using 2 HSDLs. 1 for termination and 1 for creating CWK. The termination one works fine but when I try to create the CWK, I get the below error:

You must provide only one parent record Worker and it must start on the earliest effective start date and not have an end date. A worker or person contact data file contains multiple records for the same person or the effective start date provided in the file isn't equal to the earliest effective start date of the PER_ALL_PEOPLE_F table or has an effective end date that isn't blank or equal to 31-Dec-4712. Remove any extra records for a worker or person contact in the data file. Correct the effective start date in the MERGE worker line so that the date