In some cases we send duplicate read concern to the server, due to the fact that it can be added both by:

• Certain operations, for example in FindOperation
• CommandUsingCommandMessageWireProtocol.

CreateType0Section 

Sending a duplicate read concern will return an error on the server. 
We need to respect the default hierarchy of precedence for read/write concern as also explained in our docs.

How to reproduce:

• Create a collection with non-default read concern
• Open a snapshot session
• Execute a Find 

This can happen also with transactions.