MULTIROBLOXTwo Roblox accounts on the same computer
If you cannot open a second Roblox, that is usually “Roblox already running”: the desktop Player is single-instance. Two Roblox accounts on the same computer need a second app, a helper, or a second device.
Why the second Play click fails
The Player is built so one copy owns the session. Extra Chrome profiles and “open in another browser” do not change that. Logging out is not two live clients.
What actually works
Microsoft Store Roblox plus desktop Player, MultiRoblox for extra Player processes, or another physical device. Install steps are in the accounts guide.