Bulk course creation - self-enrolment fields

In the bulk course creation tool I am encountering a problem with the self enrolment fields in the CSV file. I can get the bulk course creation tool to set up a self enrolment for the students when I create a new course, but if I try and set up a second self enrolment for staff it overwrites the first one. There doesn't seem to be a way to have more than one self enrolment instance created. Here are the fields I have tried:
shortname, fullname, category, path, templatecourse, format, maxbytes, enablecompletion, enrolment_1, enrolment_1_name, enrolment_1_password, enrolment_1_role, enrolment_2_name, enrolment_2_password, enrolment_2_role, visible