Simple program to allow running multiple Roblox client instances at once.
Download a build from the Releases
Open Multiblox before opening Roblox, and it should move to your system tray / "hidden icons".
You should be able to open multiple clients while it is there.
This is not associated with the Roblox corporation in any way.
I doubt you would get banned for using this, but keep in mind there could always be a chance.