Received message by server is kept in memory. How to clear?

I have a Server receiving messages from a client in Unity, setup like the example in the wiki.
I am sending two different messages on two different key presses, one on space bar press and the other on Q key press.
The message on space bar press is longer than the message on Q press.

Space bar message, server receives: "Client sends message on Space key press."
Q key message, server receives: "Beep beep beep on Q key press!"

If I press space bar first, and send the above message, and then press on Q, the server receives:
"Beep beep beep on Q key press!key press.", which shows that the previous message, sent on space bar was not cleared.
Is this a defect? How do you clear previous messages if not a defect?

Thank you.

Reproduce the two-message sequence using the Unity server setup described in the issue and compare the received strings. No source file or test is named; trace the server's message-receiving path and consider the issue resolved when successive messages no longer retain text from the earlier message.