[{"ID":123,"Name":"George"},{"ID":521,"Name":"Tfu"}]

db.aggregate([{"$documents":[{"ID":123,"Name":"George"},{"ID":234,"Name":"Jon"},{"ID":521,"Name":"Tfu"}]},{"$lookup":{"from":"collection","localField":"ID","foreignField":"ID","let":{"name":"$Name"},"pipeline":[{"$match":{"$expr":{"$eq":["$$name","$Name"]}}},{"$limit":1}],"as":"searchResult"}},{"$group":{"_id":null,"result":{"$push":{$ne:[[],"$searchResult"]}}}}])