Referencia usando Mongoose

app.js

var user1 = {name: 'Marcos', group: 'kjeshjiuytrdcvbnj'};
var user1 = {name: 'Vinicius', group: 'kjeshjiukjhgfkjhgfj'};

model.find({}).remove(function(){
   model.create(user1,function(err,doc){
    if(err)
        console.log(err);

    model.create(user2, function(err, doc){
        model.find({}).exec(function(err, data){
           if(err)
               console.log(err);
           console.log(data) ;
        });
    });
  }); 
});