In a large bowl, stir together flour, baking powder, baking soda, sugar, and salt; set aside. In a small bowl, beat eggs; add yogurt and mix well. Stir in buttermilk and melted butter. Pour liquid ingredients into dry ingredients all at once and whisk just until moistened. Heat griddle and 2 Tbsp. butter over medium heat (300 degrees for electric griddle). Pour 1/4 cup batter into griddle for each pancake. Cook 2 to 3 min. until underside is golden, then flip. Cook 3 to 4 min. more, until center springs back when gently pressed. Use additional butter, if necessary to prepare remaining batter. Makes 24 pancakes.