Aggregation

db.users.aggregate([
  { $group: { _id: "$name", age: { $push: "$age" } } },
  { $project: { _id: 0, name: "$_id", age: 1, matching: { $cond: [ { $eq: [{ $size: "$age" }, 1] }, 0, { $cond: [ { $eq: [ { $min: "$age" }, { $max: "$age" } ] }, 1, 0 ] } ] } } }
])

Aggregation 2

db.collection1.aggregate([
  {
    $lookup: {
      from: "collection2",
      localField: "database_name",
      foreignField: "database_name",
      as: "matches"
    }
  },
  {
    $unwind: "$matches"
  },
  {
    $match: {
      $expr: {
        $and: [
          { $eq: [ "$collection_name", "$matches.collection_name" ] },
          { $eq: [ "$database_name", "$matches.database_name" ] }
        ]
      }
    }
  },
  {
    $project: {
      _id: 0,
      database_name: 1,
      replica_set_name: 1,
      count_count: 1
    }
  }
])