Yes. That is valid JSON. A fun fact about MongoDB is it will actually store that JSON, both duplicate keys. The implication is that whatever MongoDB client you

Yes. That is valid JSON. A fun fact about MongoDB is it will actually store that JSON, both duplicate keys. The implication is that whatever MongoDB client you're using, that maps Mongo data to dictionaries/maps, is not capable of representing all valid MongoDB documents. It's important to recognize that Mongo may be storing data your client will not be able to access. I learned this when the Python client was showing one value for a key, and the Ruby client was showing another value for the same key, and neither client was showing the whole document.