If nothing happens when server is clicked on the screen due to lag, and then a second server is tried, and both go allow the player to connect independently and simultaneously, the player will see both chats mixed together, with extreme lag and potentially one or both of the server's worlds. This has been observed on servers using a host that experienced technical difficulties that generated lag on both at the same time. See attached image. Difficult to reproduce.

Using version 1.8.9, but others are potentially affected too.