Failed to create user & username already in use

Hi Experts,
We have integrated our successfactors system to qualtrics through SFTP. The current setup is that SF generates employee export file and stores insisde qualtrics. The users are imported into XM directory for the survey need. ALthough, The automation is running successfully there are some active users not imported into qulatrics system yet. It says Failed to create and username already in use. When cross checked, I confirm that username are unique ID not duplicate is found. Kindly let me know how to import those users ?


Regards,
Mohammed Javed