Preheat the oven to 350°F (180°C) and line 12 muffin cups with paper liners or coat with cooking spray.
In a small bowl, whisk together flour, baking powder, cinnamon, salt, baking soda, and allspice.
In a large bowl, whisk together mashed bananas, crushed pineapple, white sugar, brown sugar, melted butter, milk, egg, and vanilla extract.
Fold in the dry ingredients until just combined. Add pecans and fold in.
Fill the muffin cups with batter.
Make the streusel by combining flour, brown sugar, cinnamon, and salt. Cut in butter until crumbly, then stir in pecans.
Sprinkle the streusel on top of each muffin.
Bake for 20-25 minutes or until a toothpick comes out clean.
Cool for 10 minutes in the pan, then transfer to a wire rack to cool completely.