Teams that appear full but aren't

I have an assignment on GitHub classroom that enables student teams of 2 to participate. I’ve had numerous students complain and show me that even when only student is in the team, the team appears as “Full”. The Classroom assignment link shows two copies of the same student in the team, preventing another user from joining the team. Has anyone else had that problem? Are the students doing anything wrong when signing up for the teams? Is this a bug in GitHub Classroom?
Thanks
michael

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