Access to all Minecraft games (through a double account)

I found an exploit that allows access to Minecraft games through an account that is already present on the computer, as shown in the attached screenshot (I do not own Minecraft: Legends & Minecraft: Dungeon on this account).

However, Minecraft Dungeons is blocking my access to start.

Steps

• Connect a Microsoft account that owns Minecraft: Legends/Dungeon to the Xbox application (in my case, it's AegisMagenta).
• Launch the Minecraft launcher.
• Change the account in the Minecraft launcher to a new one (in my case, it's Lunarian5991).
• Press the Windows key to open Minecraft: Legends.
• When the game is open, close the launcher.
• Close the game.
• Relaunch the launcher.