TeleportService - Change of User during Teleport (Repro)

Repro:

  1. I log into Roblox Studio as username2 and open a place from my computer.
  2. From Safari, I log in as username1 and join a place.
    I am playing place as username1.
  3. I switch to Roblox Studio, and upload the place I had opened, which fails the first time. I try again (which I guess forces me to log back in to username2?)
  4. I switch back to the open Roblox Player window and do something within the game that makes me Teleport to another place instance.

When I arrive at the new place I am playing as username2 rather than username1.
This may highly unexpected depending on the game I’m playing (as it is with a game I’m developing).

Example: I use a DataStore to carry data over to the destination place during the Teleport. This contains important information that, without it, would corrupt the playing experience entirely. The data is stored under the key formed by converting the player’s userId to a string (which, if I change users, means I could come over with mismatched data or no data at all).

May be relevant for the repro:
I am on my MacBook Pro 15" Retina Mid-2014 running OS X Yosemite 10.10.1