[Gameplay / Client] Somehow managed to get someone else's mastery pages in champ select.

I duo'd with a friend this morning, Normal Draft, and when we got into a lobby someone very quickly dodged. It was quick enough I didn't even see my role.

The next lobby popped and when I entered I noticed my mastery pages were off. They had names I wasn't familiar with. I listed some of the names in the chat, and my friend told me that those were HIS masteries. When I selected one of them, I received and error message that stated "No good error message could be found" or something like that. It was honestly hysterical. I tried to select several pages and finally when I opened the drop-down menu, my own mastery pages returned and I was able to select one.

I'm going to assume the issue happened because me and my friend were queued together and someone exited the lobby very very quickly after they accepted and the lobby popped. That's honestly the only thing I can think of on recreating that bug.