In the meantime, you can avoid the issues by not dismissing any Tems in your squads (swap them instead). Choosing the dismiss option is what causes the duplication and disappearing issues.
If you currently have a broken squad, reconnecting to the game will fix the issue.
We're aware of the current Showdown squad problems with duplicated or missing Tems and wrong techniques. Unfortunately, after fixing some issues yesterday, these new issues are client-related so we can't fix them on the fly and need a new patch, which takes longer.