Hi Beautymountainfarm2, My understanding of the double buzz is the lips are to tight for the note you are trying to play. I suggest doing some really soft ‘pu’ attacks followed by a long soft tone.
Once you have done that starting on the Bb really softly, start doing some gradual crescendos to see where it breaks up, then rest and go up to B, C etc etc.
You are realigning so this phenomenon is not unusual.
Stay in touch.