The same account joining a realm at the same time will crash both devices
Comments 2
Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
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What specific devices are you using? You should get an error message when you try to do this though, as you cannot connect from multiple devices on the same account at the same time.