[{"Id":"1","Info":"X","Date":"10/1"},{"Id":"2","Info":"X","Date":"13/2"},{"Id":"3","Info":"Y","Date":"13/2"},{"Id":"4","Info":"X","Date":"10/1"},{"Id":"5","Info":"X","Date":"10/1"},{"Id":"6","Info":"X","Date":"13/2"},]

db.collection.aggregate([{"$project":{"Id":1,"Date":1,"info":"$Info"}},{"$group":{"_id":{date:"$Date",info:"$info"},"Id":{"$addToSet":"$Id"}}},{"$project":{"_id":0,"Info":"$_id.info","Date":"$_id.date","Id":1}}])