Depends upon the variety I assume. My Nam Doc Mai can fruit 2-3 times a year...generally only 2. Environmental conditions can possibly contribute to this as well along with pruning. Mangos often have "mixed" signals on blooming and growth flushes that push flowers and new leaves from the same panacle. Post this question on the Tropical Fruits forum. You might get a better answer there.

My "Tommy Atkins" is having a second bloom. It is ejecting the original fruit. Also, I have noticed others in the neighborhood are doing the same.