sdev dynamic directories can be created multiple times
sdev has a simple matching system to determine if it should switch about its vnops for special types of dyanmic nodes. If you create another one of these you now have two copies of these nodes in the namespace, definitely not quite an intended behavior.
The solution here is to ensure that you are only under /dev when these are created. This was part of the original intent of the system as far as we can tell. Having dynamic directories at any point in the name space is tricky and requires a lot of careful though. As such, until we have such a need for something we are restricted to doing what we know is safe.