To add to this: if you use the same designed tile but with different assigned colors is that a different tile? Eg a darker green pixel in the top left corner with a light green background.
This would also count as a unique tile. If you were programming the game yourself, you could change the palettes, but since we're using GB Studio (and also trying to make it more accessible) this is not an option. The best bet is to use the tile counter to see if your tile is unique or not.
