/users/extended bug: Fetching students and parents together returns duplicates

Hi all, I'm getting duplicate user records when fetching students and parents together.

• Steps to reproduce:
  
  GET /users/extended?base_role_ids=14,16
  
  However, this doesn't happen for all schools. It's happening for one particular school.
  
• Expected result: The endpoint returns one record for each student and parent.
• Actual result: The endpoint returns duplicate records.
  
  449 IDs occur more than once in the results.
  650 IDs occur only once in the results.
  
• Workaround: Make two API calls:
  
  /users/extended?base_role_ids=14
  /users/extended?base_role_ids=16
  
  No duplicate records are returned.