XML serialize multiple classes

Question

So I've got a bit of a problem I'm made a class that i have to use 7 times (one for each day of the week) I have the serialize set this way

 FileStream stream = new FileStream("C:\\employee.xml", FileMode.OpenOrCreate);
            XmlSerializer serializer = new XmlSerializer(typeof(Day));
            serializer.Serialize(stream, monday);
            serializer.Serialize(stream, tuesday);
            serializer.Serialize(stream, wednesday);
            serializer.Serialize(stream, thursday);
            serializer.Serialize(stream, friday);
            serializer.Serialize(stream, saturday);
            serializer.Serialize(stream, sunday);

problem is when I unserialize it only works if i only save the class once, is there anything that has to be done differently for more then 1 instance of the same class?

 FileStream stream = new FileStream("C:\\employee.xml", FileMode.Open);
            XmlSerializer serializer = new XmlSerializer(typeof(Day));
            monday = (Day)serializer.Deserialize(stream);

Thanks :)