The bug

When a chat message is sent, it is also saved to the history, so you can easily press UP to send the same message later. This makes it easy to run repeated commands and so on. However, running a message from history will then save it to history a second time, adding a needless entry that makes other messages harder to get to.

How to reproduce

1. Type "hello" and send it in chat
2. Type "message" and send it in chat
3. Open chat, then press up and enter to send message again
4. Repeat 5 times
5. Open chat, then press up twice
Expected result
Previous message "hello" appears
Actual result
Nothing changes in the message box. You have to press up several more times to get the original message. History was clogged with duplicate consecutive entries.