Niantic and Pokemon Go announced earlier this month that players from all around the globe will be able to stack multiple Star Piece, Lucky Egg, and Incense at once. Now, this feature is live and you can stack up to 24 hours of boosts at one time.
The capability of stacking effects of multiple Star Piece, Lucky Egg, and Incense at the same time, was announced on April 15, and today, the boost-item stacking feature is live. With this new feature, a Trainer will be able to have 24 hours of boosts functioning at the same time.
Each of the power-ups is active for 30 minutes, but with this new feature, you can activate multiple Star Pieces, Lucky Eggs, or Incense. You can activate 200 of each item, but please be aware that once an item is active, it can not be returned back to your Item Bag.