Transaction Group Stored Procedure Question

Just curious

Does any one know what would happen if the stars aligned and I called triggered two transaction groups stored procedures simultaneously? Different data, same stored procedure and the exact same time. I haven't had a failure yet, but I'm wondering if I have just been lucky

Entirely depends on the stored procedure. Well-written stored procedures should be compatible with parallel execution. Ignition certainly will call them in parallel if the timing lines up.