I'm thinking that the bees make queen cups all the time, as our friends are saying. I bet this is for practice. The bees want the best of the best for their new queen, the most perfect cell that they can make, if they have lots of great cells present in the hive, then they can choose the most beautiful and elaborate :). She should be in the perfect place, only made for her alone.
Maybe another reason could be that they have the cells ready, just in case, it is like the saying "be prepared", we should all be that way :roll: Have a wonderful day, love our life we're livin'. Cindi