Can a Orion Context Broker entity have two attributes with the same name but different type?
If yes, is it controlled by Orion? Is an error returned when such an entity is created?
If no, what happens when a convenience operation tries to get the value of one of the 2 attributes (AFAIK, the attribute type is not passed in the operation).
From Orion 0.17.0 on, type is no longer used to identify an attribute. Thus, attributes are identified by name plus (optionally) metadata ID. I will assume version >=0.17.0 in the rest of this answer.
Orion doesn't control violation of that rule when processing operations to create entities or append attribute on existing entities. In those cases, only one instance of the attributes with the same identification is taken an stored in the DB, the others are ignored. It is not recommended at all that a client do such kind of operations (in the future, Orion may check that condition and return an error to the client).
Taking account the above paragraph and regarding what happens when a convenience operation tries to get the value of one of the 2 attributes (AFAIK, the attribute type is not passed in the operation)? note that situation cannot happend. I mean, at Orion DB will never store two attributes with the same identification associated to the same entity.
Some additional comment regarding metadata ID: I don't recommend the use of metadata ID as any potential ID can be included in the name and you will get your client much simpler, e.g. you don't need and attribute with name=temperature and id=outside if you use name=temperature::outside or any other namespacing technique.
