Q: Can a student be enrolled in a Homeroom class and Intervention class at the same time?
A: A student can only be enrolled in one teacher's class at a time. The only way for a different teacher to have that student on his/her class list, is to "unenroll" the student from the homeroom/main teacher's class for the period of time that the student is with the 2nd teacher. The advantage of this is that the intervention teacher has them on his/her class list, and is able to see all the data. The disadvantage is that the homeroom teacher loses the ability to test that student in any subject area, and see their data until the student is moved back.
Here are directions for moving a student between classes.
Another option that the teachers have is to share usernames/passwords. So the intervention teacher would sign on as the homeroom teacher to assess that student in the intervention subject area.