you might consider using two more querystring parameters:
Create a Bookmark with no selection, and use it as the first agrument in your URL. This will "reset" (clear) the selections before setting a new selection with your "select=LBxx" argument. Should fix the explained problem. Using sheet allows you to directly open a specific sheet and you might not require the condional showing of sheets based on the listbox values. ?
Querystring parameters are well explained here: