Issue Summary

MongoDB Query Runner displays duplicated columns on querying without fields.

Steps to Reproduce

1. Insert multiple records

test> db.hoge.find()
[
  { _id: ObjectId('6569ecd1214c2278faf58ca3'), name: 'test' },
  { _id: ObjectId('6569ee53d53db7930aaa0cc0'), name: 'test2', age: 10 }
]

2. Send a query without fields

{"collection": "hoge"}

3. The columns are "_id", "name", "_id", "name", "age". The expected columns are "_id", "name", "age".
   

Technical details:

• Redash Version: master branch
• Browser/OS: Chrome / Docker
• How did you install Redash: