1) To get the access group list associated with the operator, you can remove the F2 filter from the above report and add the pyAccessGroupAdditional column.
Please find the below screenshot for more details.
2) As we are joining with 2 tables, in the first join say it gets 2 records based on the condition and if we do the second join and 2 records are present, then in the main report 2x2=4 records will be shown. I think this is expected as per OOTB.
If we need unique list, then we can have 2 seperate reports for Workgroup and Workbasket, and join with respective index class in each report.