Put the summary of the bug you're having here

What I expected to happen was...:
Easily being able to log onto a server after my friend and I changed our Minecraft names.

What actually happened was...:
Me and my friend had both changed our minecraft names, and after we did that, we went back on to minecraft to go play on a server together, but when we clicked, it said "Failed to connect to server; not authenticated with Minecraft.net"." We tried going on multiple servers, but the same thing popped up over and over again. PLEASE help. I'm not sure if this is a problem with us changing our names, or a general minecraft problem. Also; we went on singleplayer to see if our names changed; and they didn't, after we typed in our "single player chat", I guess you could call it.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
(I'm not sure if I'm going to do this right):
2. ...Change your minecraft name
3. ...Try going on a Minecraft server