Yes, and I quote "These properties remain opaque to the application server during the connection request flow.".
It is up to the JCA container to provide pooling of managed connections (not the connections) and implement that pool such that the resource adapter provider can count on the requirements specified in section 9.1.9.
You have to implement section 9.1.9 and keep track of the relationship between a connection and its managed connection. Just like always.